linux.git/net/sched/act_api.c, branch v5.10.258 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc() 2024-07-05T07:12:38+00:00 David Ruth druth@chromium.org 2024-06-14T19:03:26+00:00 c6a7da65a296745535a964be1019ec7691b0cb90 [ Upstream commit d864319871b05fadd153e0aede4811ca7008f5d6 ] syzbot found hanging tasks waiting on rtnl_lock [1] A reproducer is available in the syzbot bug. When a request to add multiple actions with the same index is sent, the second request will block forever on the first request. This holds rtnl_lock, and causes tasks to hang. Return -EAGAIN to prevent infinite looping, while keeping documented behavior. [1] INFO: task kworker/1:0:5088 blocked for more than 143 seconds. Not tainted 6.9.0-rc4-syzkaller-00173-g3cdb45594619 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:0 state:D stack:23744 pid:5088 tgid:5088 ppid:2 flags:0x00004000 Workqueue: events_power_efficient reg_check_chans_work Call Trace: <TASK> context_switch kernel/sched/core.c:5409 [inline] __schedule+0xf15/0x5d00 kernel/sched/core.c:6746 __schedule_loop kernel/sched/core.c:6823 [inline] schedule+0xe7/0x350 kernel/sched/core.c:6838 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6895 __mutex_lock_common kernel/locking/mutex.c:684 [inline] __mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752 wiphy_lock include/net/cfg80211.h:5953 [inline] reg_leave_invalid_chans net/wireless/reg.c:2466 [inline] reg_check_chans_work+0x10a/0x10e0 net/wireless/reg.c:2481 Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action") Reported-by: syzbot+b87c222546179f4513a7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b87c222546179f4513a7 Signed-off-by: David Ruth <druth@chromium.org> Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20240614190326.1349786-1-druth@chromium.org Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d864319871b05fadd153e0aede4811ca7008f5d6 ]

syzbot found hanging tasks waiting on rtnl_lock [1]

A reproducer is available in the syzbot bug.

When a request to add multiple actions with the same index is sent, the
second request will block forever on the first request. This holds
rtnl_lock, and causes tasks to hang.

Return -EAGAIN to prevent infinite looping, while keeping documented
behavior.

[1]

INFO: task kworker/1:0:5088 blocked for more than 143 seconds.
Not tainted 6.9.0-rc4-syzkaller-00173-g3cdb45594619 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:0 state:D stack:23744 pid:5088 tgid:5088 ppid:2 flags:0x00004000
Workqueue: events_power_efficient reg_check_chans_work
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5409 [inline]
__schedule+0xf15/0x5d00 kernel/sched/core.c:6746
__schedule_loop kernel/sched/core.c:6823 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6838
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6895
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
wiphy_lock include/net/cfg80211.h:5953 [inline]
reg_leave_invalid_chans net/wireless/reg.c:2466 [inline]
reg_check_chans_work+0x10a/0x10e0 net/wireless/reg.c:2481

Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action")
Reported-by: syzbot+b87c222546179f4513a7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b87c222546179f4513a7
Signed-off-by: David Ruth <druth@chromium.org>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20240614190326.1349786-1-druth@chromium.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net/sched: act_api: rely on rcu in tcf_idr_check_alloc 2024-07-05T07:12:38+00:00 Pedro Tammela pctammela@mojatatu.com 2023-12-11T18:18:06+00:00 66c7aa157a38d93947b32c0d309889369a27e8e2 [ Upstream commit 4b55e86736d5b492cf689125da2600f59c7d2c39 ] Instead of relying only on the idrinfo->lock mutex for bind/alloc logic, rely on a combination of rcu + mutex + atomics to better scale the case where multiple rtnl-less filters are binding to the same action object. Action binding happens when an action index is specified explicitly and an action exists which such index exists. Example: tc actions add action drop index 1 tc filter add ... matchall action drop index 1 tc filter add ... matchall action drop index 1 tc filter add ... matchall action drop index 1 tc filter ls ... filter protocol all pref 49150 matchall chain 0 filter protocol all pref 49150 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 filter protocol all pref 49151 matchall chain 0 filter protocol all pref 49151 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 filter protocol all pref 49152 matchall chain 0 filter protocol all pref 49152 matchall chain 0 handle 0x1 not_in_hw action order 1: gact action drop random type none pass val 0 index 1 ref 4 bind 3 When no index is specified, as before, grab the mutex and allocate in the idr the next available id. In this version, as opposed to before, it's simplified to store the -EBUSY pointer instead of the previous alloc + replace combination. When an index is specified, rely on rcu to find if there's an object in such index. If there's none, fallback to the above, serializing on the mutex and reserving the specified id. If there's one, it can be an -EBUSY pointer, in which case we just try again until it's an action, or an action. Given the rcu guarantees, the action found could be dead and therefore we need to bump the refcount if it's not 0, handling the case it's in fact 0. As bind and the action refcount are already atomics, these increments can happen without the mutex protection while many tcf_idr_check_alloc race to bind to the same action instance. In case binding encounters a parallel delete or add, it will return -EAGAIN in order to try again. Both filter and action apis already have the retry machinery in-place. In case it's an unlocked filter it retries under the rtnl lock. Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Reviewed-by: Vlad Buslov <vladbu@nvidia.com> Link: https://lore.kernel.org/r/20231211181807.96028-2-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: d864319871b0 ("net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc()") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4b55e86736d5b492cf689125da2600f59c7d2c39 ]

Instead of relying only on the idrinfo->lock mutex for
bind/alloc logic, rely on a combination of rcu + mutex + atomics
to better scale the case where multiple rtnl-less filters are
binding to the same action object.

Action binding happens when an action index is specified explicitly and
an action exists which such index exists. Example:
  tc actions add action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter ls ...
     filter protocol all pref 49150 matchall chain 0 filter protocol all pref 49150 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

   filter protocol all pref 49151 matchall chain 0 filter protocol all pref 49151 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

   filter protocol all pref 49152 matchall chain 0 filter protocol all pref 49152 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

When no index is specified, as before, grab the mutex and allocate
in the idr the next available id. In this version, as opposed to before,
it's simplified to store the -EBUSY pointer instead of the previous
alloc + replace combination.

When an index is specified, rely on rcu to find if there's an object in
such index. If there's none, fallback to the above, serializing on the
mutex and reserving the specified id. If there's one, it can be an -EBUSY
pointer, in which case we just try again until it's an action, or an action.
Given the rcu guarantees, the action found could be dead and therefore
we need to bump the refcount if it's not 0, handling the case it's
in fact 0.

As bind and the action refcount are already atomics, these increments can
happen without the mutex protection while many tcf_idr_check_alloc race
to bind to the same action instance.

In case binding encounters a parallel delete or add, it will return
-EAGAIN in order to try again. Both filter and action apis already
have the retry machinery in-place. In case it's an unlocked filter it
retries under the rtnl lock.

Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Link: https://lore.kernel.org/r/20231211181807.96028-2-pctammela@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: d864319871b0 ("net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
net/sched: act_api: Notify user space if any actions were flushed before error 2022-07-07T15:52:18+00:00 Victor Nogueira victor@mojatatu.com 2022-06-23T14:07:41+00:00 ac12337229eacd47c8a6ac59d3a026dd3ad3f058 commit 76b39b94382f9e0a639e1c70c3253de248cc4c83 upstream. If during an action flush operation one of the actions is still being referenced, the flush operation is aborted and the kernel returns to user space with an error. However, if the kernel was able to flush, for example, 3 actions and failed on the fourth, the kernel will not notify user space that it deleted 3 actions before failing. This patch fixes that behaviour by notifying user space of how many actions were deleted before flush failed and by setting extack with a message describing what happened. Fixes: 55334a5db5cd ("net_sched: act: refuse to remove bound action outside") Signed-off-by: Victor Nogueira <victor@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 76b39b94382f9e0a639e1c70c3253de248cc4c83 upstream.

If during an action flush operation one of the actions is still being
referenced, the flush operation is aborted and the kernel returns to
user space with an error. However, if the kernel was able to flush, for
example, 3 actions and failed on the fourth, the kernel will not notify
user space that it deleted 3 actions before failing.

This patch fixes that behaviour by notifying user space of how many
actions were deleted before flush failed and by setting extack with a
message describing what happened.

Fixes: 55334a5db5cd ("net_sched: act: refuse to remove bound action outside")
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: sched: limit TC_ACT_REPEAT loops 2022-02-23T11:01:07+00:00 Eric Dumazet edumazet@google.com 2022-02-15T23:53:05+00:00 797b380f0756354b39f7487c362ea203cf3e3e80 commit 5740d068909676d4bdb5c9c00c37a83df7728909 upstream. We have been living dangerously, at the mercy of malicious users, abusing TC_ACT_REPEAT, as shown by this syzpot report [1]. Add an arbitrary limit (32) to the number of times an action can return TC_ACT_REPEAT. v2: switch the limit to 32 instead of 10. Use net_warn_ratelimited() instead of pr_err_once(). [1] (C repro available on demand) rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-...!: (10500 ticks this GP) idle=021/1/0x4000000000000000 softirq=5592/5592 fqs=0 (t=10502 jiffies g=5305 q=190) rcu: rcu_preempt kthread timer wakeup didn't happen for 10502 jiffies! g5305 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=3527 rcu: rcu_preempt kthread starved for 10505 jiffies! g5305 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:29344 pid: 14 ppid: 2 flags:0x00004000 Call Trace: <TASK> context_switch kernel/sched/core.c:4986 [inline] __schedule+0xab2/0x4db0 kernel/sched/core.c:6295 schedule+0xd2/0x260 kernel/sched/core.c:6368 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1963 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2136 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 3646 Comm: syz-executor358 Not tainted 5.17.0-rc3-syzkaller-00149-gbf8e59fd315f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline] RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:437 [inline] RIP: 0010:__pv_queued_spin_lock_slowpath+0x3b8/0xb40 kernel/locking/qspinlock.c:508 Code: 48 89 eb c6 45 01 01 41 bc 00 80 00 00 48 c1 e9 03 83 e3 07 41 be 01 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8d 2c 01 eb 0c <f3> 90 41 83 ec 01 0f 84 72 04 00 00 41 0f b6 45 00 38 d8 7f 08 84 RSP: 0018:ffffc9000283f1b0 EFLAGS: 00000206 RAX: 0000000000000003 RBX: 0000000000000000 RCX: 1ffff1100fc0071e RDX: 0000000000000001 RSI: 0000000000000201 RDI: 0000000000000000 RBP: ffff88807e0038f0 R08: 0000000000000001 R09: ffffffff8ffbf9ff R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000004c1e R13: ffffed100fc0071e R14: 0000000000000001 R15: ffff8880b9c3aa80 FS: 00005555562bf300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffdbfef12b8 CR3: 00000000723c2000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:115 spin_lock_bh include/linux/spinlock.h:354 [inline] sch_tree_lock include/net/sch_generic.h:610 [inline] sch_tree_lock include/net/sch_generic.h:605 [inline] prio_tune+0x3b9/0xb50 net/sched/sch_prio.c:211 prio_init+0x5c/0x80 net/sched/sch_prio.c:244 qdisc_create.constprop.0+0x44a/0x10f0 net/sched/sch_api.c:1253 tc_modify_qdisc+0x4c5/0x1980 net/sched/sch_api.c:1660 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5594 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343 netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:725 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2413 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2496 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f7ee98aae99 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdbfef12d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007ffdbfef1300 RCX: 00007f7ee98aae99 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d R10: 000000000000000d R11: 0000000000000246 R12: 00007ffdbfef12f0 R13: 00000000000f4240 R14: 000000000004ca47 R15: 00007ffdbfef12e4 </TASK> INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.293 msecs NMI backtrace for cpu 1 CPU: 1 PID: 3260 Comm: kworker/1:3 Not tainted 5.17.0-rc3-syzkaller-00149-gbf8e59fd315f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: mld mld_ifc_work Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343 print_cpu_stall kernel/rcu/tree_stall.h:604 [inline] check_cpu_stall kernel/rcu/tree_stall.h:688 [inline] rcu_pending kernel/rcu/tree.c:3919 [inline] rcu_sched_clock_irq.cold+0x5c/0x759 kernel/rcu/tree.c:2617 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0xc/0x70 kernel/kcov.c:286 Code: 00 00 00 48 89 7c 30 e8 48 89 4c 30 f0 4c 89 54 d8 20 48 89 10 5b c3 0f 1f 80 00 00 00 00 41 89 f8 bf 03 00 00 00 4c 8b 14 24 <89> f1 65 48 8b 34 25 00 70 02 00 e8 14 f9 ff ff 84 c0 74 4b 48 8b RSP: 0018:ffffc90002c5eea8 EFLAGS: 00000246 RAX: 0000000000000007 RBX: ffff88801c625800 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: ffff8880137d3100 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff874fcd88 R11: 0000000000000000 R12: ffff88801d692dc0 R13: ffff8880137d3104 R14: 0000000000000000 R15: ffff88801d692de8 tcf_police_act+0x358/0x11d0 net/sched/act_police.c:256 tcf_action_exec net/sched/act_api.c:1049 [inline] tcf_action_exec+0x1a6/0x530 net/sched/act_api.c:1026 tcf_exts_exec include/net/pkt_cls.h:326 [inline] route4_classify+0xef0/0x1400 net/sched/cls_route.c:179 __tcf_classify net/sched/cls_api.c:1549 [inline] tcf_classify+0x3e8/0x9d0 net/sched/cls_api.c:1615 prio_classify net/sched/sch_prio.c:42 [inline] prio_enqueue+0x3a7/0x790 net/sched/sch_prio.c:75 dev_qdisc_enqueue+0x40/0x300 net/core/dev.c:3668 __dev_xmit_skb net/core/dev.c:3756 [inline] __dev_queue_xmit+0x1f61/0x3660 net/core/dev.c:4081 neigh_hh_output include/net/neighbour.h:533 [inline] neigh_output include/net/neighbour.h:547 [inline] ip_finish_output2+0x14dc/0x2170 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:306 [inline] __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:288 ip_finish_output+0x32/0x200 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_output+0x196/0x310 net/ipv4/ip_output.c:430 dst_output include/net/dst.h:451 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126 iptunnel_xmit+0x628/0xa50 net/ipv4/ip_tunnel_core.c:82 geneve_xmit_skb drivers/net/geneve.c:966 [inline] geneve_xmit+0x10c8/0x3530 drivers/net/geneve.c:1077 __netdev_start_xmit include/linux/netdevice.h:4683 [inline] netdev_start_xmit include/linux/netdevice.h:4697 [inline] xmit_one net/core/dev.c:3473 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489 __dev_queue_xmit+0x2985/0x3660 net/core/dev.c:4116 neigh_hh_output include/net/neighbour.h:533 [inline] neigh_output include/net/neighbour.h:547 [inline] ip6_finish_output2+0xf7a/0x14f0 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe90 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:451 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] mld_sendpack+0x9a3/0xe40 net/ipv6/mcast.c:1826 mld_send_cr net/ipv6/mcast.c:2127 [inline] mld_ifc_work+0x71c/0xdc0 net/ipv6/mcast.c:2659 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> ---------------- Code disassembly (best guess): 0: 48 89 eb mov %rbp,%rbx 3: c6 45 01 01 movb $0x1,0x1(%rbp) 7: 41 bc 00 80 00 00 mov $0x8000,%r12d d: 48 c1 e9 03 shr $0x3,%rcx 11: 83 e3 07 and $0x7,%ebx 14: 41 be 01 00 00 00 mov $0x1,%r14d 1a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 21: fc ff df 24: 4c 8d 2c 01 lea (%rcx,%rax,1),%r13 28: eb 0c jmp 0x36 * 2a: f3 90 pause <-- trapping instruction 2c: 41 83 ec 01 sub $0x1,%r12d 30: 0f 84 72 04 00 00 je 0x4a8 36: 41 0f b6 45 00 movzbl 0x0(%r13),%eax 3b: 38 d8 cmp %bl,%al 3d: 7f 08 jg 0x47 3f: 84 .byte 0x84 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Jiri Pirko <jiri@resnulli.us> Reported-by: syzbot <syzkaller@googlegroups.com> Link: https://lore.kernel.org/r/20220215235305.3272331-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5740d068909676d4bdb5c9c00c37a83df7728909 upstream.

We have been living dangerously, at the mercy of malicious users,
abusing TC_ACT_REPEAT, as shown by this syzpot report [1].

Add an arbitrary limit (32) to the number of times an action can
return TC_ACT_REPEAT.

v2: switch the limit to 32 instead of 10.
    Use net_warn_ratelimited() instead of pr_err_once().

[1] (C repro available on demand)

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu:    1-...!: (10500 ticks this GP) idle=021/1/0x4000000000000000 softirq=5592/5592 fqs=0
        (t=10502 jiffies g=5305 q=190)
rcu: rcu_preempt kthread timer wakeup didn't happen for 10502 jiffies! g5305 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu:    Possible timer handling issue on cpu=0 timer-softirq=3527
rcu: rcu_preempt kthread starved for 10505 jiffies! g5305 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu:    Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:I stack:29344 pid:   14 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:4986 [inline]
 __schedule+0xab2/0x4db0 kernel/sched/core.c:6295
 schedule+0xd2/0x260 kernel/sched/core.c:6368
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1963
 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2136
 kthread+0x2e9/0x3a0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3646 Comm: syz-executor358 Not tainted 5.17.0-rc3-syzkaller-00149-gbf8e59fd315f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline]
RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline]
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:437 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x3b8/0xb40 kernel/locking/qspinlock.c:508
Code: 48 89 eb c6 45 01 01 41 bc 00 80 00 00 48 c1 e9 03 83 e3 07 41 be 01 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8d 2c 01 eb 0c <f3> 90 41 83 ec 01 0f 84 72 04 00 00 41 0f b6 45 00 38 d8 7f 08 84
RSP: 0018:ffffc9000283f1b0 EFLAGS: 00000206
RAX: 0000000000000003 RBX: 0000000000000000 RCX: 1ffff1100fc0071e
RDX: 0000000000000001 RSI: 0000000000000201 RDI: 0000000000000000
RBP: ffff88807e0038f0 R08: 0000000000000001 R09: ffffffff8ffbf9ff
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000004c1e
R13: ffffed100fc0071e R14: 0000000000000001 R15: ffff8880b9c3aa80
FS:  00005555562bf300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdbfef12b8 CR3: 00000000723c2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
 do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:115
 spin_lock_bh include/linux/spinlock.h:354 [inline]
 sch_tree_lock include/net/sch_generic.h:610 [inline]
 sch_tree_lock include/net/sch_generic.h:605 [inline]
 prio_tune+0x3b9/0xb50 net/sched/sch_prio.c:211
 prio_init+0x5c/0x80 net/sched/sch_prio.c:244
 qdisc_create.constprop.0+0x44a/0x10f0 net/sched/sch_api.c:1253
 tc_modify_qdisc+0x4c5/0x1980 net/sched/sch_api.c:1660
 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5594
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x539/0x7e0 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x904/0xe00 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:705 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:725
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2413
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2467
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2496
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f7ee98aae99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdbfef12d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffdbfef1300 RCX: 00007f7ee98aae99
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d
R10: 000000000000000d R11: 0000000000000246 R12: 00007ffdbfef12f0
R13: 00000000000f4240 R14: 000000000004ca47 R15: 00007ffdbfef12e4
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.293 msecs
NMI backtrace for cpu 1
CPU: 1 PID: 3260 Comm: kworker/1:3 Not tainted 5.17.0-rc3-syzkaller-00149-gbf8e59fd315f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: mld mld_ifc_work
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343
 print_cpu_stall kernel/rcu/tree_stall.h:604 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:688 [inline]
 rcu_pending kernel/rcu/tree.c:3919 [inline]
 rcu_sched_clock_irq.cold+0x5c/0x759 kernel/rcu/tree.c:2617
 update_process_times+0x16d/0x200 kernel/time/timer.c:1785
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1428
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0xc/0x70 kernel/kcov.c:286
Code: 00 00 00 48 89 7c 30 e8 48 89 4c 30 f0 4c 89 54 d8 20 48 89 10 5b c3 0f 1f 80 00 00 00 00 41 89 f8 bf 03 00 00 00 4c 8b 14 24 <89> f1 65 48 8b 34 25 00 70 02 00 e8 14 f9 ff ff 84 c0 74 4b 48 8b
RSP: 0018:ffffc90002c5eea8 EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffff88801c625800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: ffff8880137d3100 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff874fcd88 R11: 0000000000000000 R12: ffff88801d692dc0
R13: ffff8880137d3104 R14: 0000000000000000 R15: ffff88801d692de8
 tcf_police_act+0x358/0x11d0 net/sched/act_police.c:256
 tcf_action_exec net/sched/act_api.c:1049 [inline]
 tcf_action_exec+0x1a6/0x530 net/sched/act_api.c:1026
 tcf_exts_exec include/net/pkt_cls.h:326 [inline]
 route4_classify+0xef0/0x1400 net/sched/cls_route.c:179
 __tcf_classify net/sched/cls_api.c:1549 [inline]
 tcf_classify+0x3e8/0x9d0 net/sched/cls_api.c:1615
 prio_classify net/sched/sch_prio.c:42 [inline]
 prio_enqueue+0x3a7/0x790 net/sched/sch_prio.c:75
 dev_qdisc_enqueue+0x40/0x300 net/core/dev.c:3668
 __dev_xmit_skb net/core/dev.c:3756 [inline]
 __dev_queue_xmit+0x1f61/0x3660 net/core/dev.c:4081
 neigh_hh_output include/net/neighbour.h:533 [inline]
 neigh_output include/net/neighbour.h:547 [inline]
 ip_finish_output2+0x14dc/0x2170 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:288
 ip_finish_output+0x32/0x200 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0x196/0x310 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:451 [inline]
 ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x628/0xa50 net/ipv4/ip_tunnel_core.c:82
 geneve_xmit_skb drivers/net/geneve.c:966 [inline]
 geneve_xmit+0x10c8/0x3530 drivers/net/geneve.c:1077
 __netdev_start_xmit include/linux/netdevice.h:4683 [inline]
 netdev_start_xmit include/linux/netdevice.h:4697 [inline]
 xmit_one net/core/dev.c:3473 [inline]
 dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3489
 __dev_queue_xmit+0x2985/0x3660 net/core/dev.c:4116
 neigh_hh_output include/net/neighbour.h:533 [inline]
 neigh_output include/net/neighbour.h:547 [inline]
 ip6_finish_output2+0xf7a/0x14f0 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 __ip6_finish_output+0x61e/0xe90 net/ipv6/ip6_output.c:170
 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224
 dst_output include/net/dst.h:451 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 mld_sendpack+0x9a3/0xe40 net/ipv6/mcast.c:1826
 mld_send_cr net/ipv6/mcast.c:2127 [inline]
 mld_ifc_work+0x71c/0xdc0 net/ipv6/mcast.c:2659
 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307
 worker_thread+0x657/0x1110 kernel/workqueue.c:2454
 kthread+0x2e9/0x3a0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
----------------
Code disassembly (best guess):
   0:   48 89 eb                mov    %rbp,%rbx
   3:   c6 45 01 01             movb   $0x1,0x1(%rbp)
   7:   41 bc 00 80 00 00       mov    $0x8000,%r12d
   d:   48 c1 e9 03             shr    $0x3,%rcx
  11:   83 e3 07                and    $0x7,%ebx
  14:   41 be 01 00 00 00       mov    $0x1,%r14d
  1a:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
  21:   fc ff df
  24:   4c 8d 2c 01             lea    (%rcx,%rax,1),%r13
  28:   eb 0c                   jmp    0x36
* 2a:   f3 90                   pause <-- trapping instruction
  2c:   41 83 ec 01             sub    $0x1,%r12d
  30:   0f 84 72 04 00 00       je     0x4a8
  36:   41 0f b6 45 00          movzbl 0x0(%r13),%eax
  3b:   38 d8                   cmp    %bl,%al
  3d:   7f 08                   jg     0x47
  3f:   84                      .byte 0x84

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20220215235305.3272331-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: sched: fix error return code in tcf_del_walker() 2021-07-19T07:44:51+00:00 Yang Yingliang yangyingliang@huawei.com 2021-06-17T08:02:07+00:00 92a9fb51e5ecd009081a1c311ea90afe83379438 [ Upstream commit 55d96f72e8ddc0a294e0b9c94016edbb699537e1 ] When nla_put_u32() fails, 'ret' could be 0, it should return error code in tcf_del_walker(). Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 55d96f72e8ddc0a294e0b9c94016edbb699537e1 ]

When nla_put_u32() fails, 'ret' could be 0, it should
return error code in tcf_del_walker().

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Revert "net: sched: bump refcount for new action in ACT replace mode" 2021-04-14T06:42:14+00:00 Vlad Buslov vladbu@nvidia.com 2021-04-07T15:36:02+00:00 b451aed56348ee1202d0dc6f52645104b06a2206 commit 4ba86128ba077fbb7d86516ae24ed642e6c3adef upstream. This reverts commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149. Following commit in series fixes the issue without introducing regression in error rollback of tcf_action_destroy(). Signed-off-by: Vlad Buslov <vladbu@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4ba86128ba077fbb7d86516ae24ed642e6c3adef upstream.

This reverts commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149.

Following commit in series fixes the issue without introducing regression
in error rollback of tcf_action_destroy().

Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: sched: bump refcount for new action in ACT replace mode 2021-04-14T06:42:12+00:00 Kumar Kartikeya Dwivedi memxor@gmail.com 2021-03-29T22:53:23+00:00 300368c59cf0af517f7188793bdcebc3962d8e9b commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149 upstream. Currently, action creation using ACT API in replace mode is buggy. When invoking for non-existent action index 42, tc action replace action bpf obj foo.o sec <xyz> index 42 kernel creates the action, fills up the netlink response, and then just deletes the action after notifying userspace. tc action show action bpf doesn't list the action. This happens due to the following sequence when ovr = 1 (replace mode) is enabled: tcf_idr_check_alloc is used to atomically check and either obtain reference for existing action at index, or reserve the index slot using a dummy entry (ERR_PTR(-EBUSY)). This is necessary as pointers to these actions will be held after dropping the idrinfo lock, so bumping the reference count is necessary as we need to insert the actions, and notify userspace by dumping their attributes. Finally, we drop the reference we took using the tcf_action_put_many call in tcf_action_add. However, for the case where a new action is created due to free index, its refcount remains one. This when paired with the put_many call leads to the kernel setting up the action, notifying userspace of its creation, and then tearing it down. For existing actions, the refcount is still held so they remain unaffected. Fortunately due to rtnl_lock serialization requirement, such an action with refcount == 1 will not be concurrently deleted by anything else, at best CLS API can move its refcount up and down by binding to it after it has been published from tcf_idr_insert_many. Since refcount is atleast one until put_many call, CLS API cannot delete it. Also __tcf_action_put release path already ensures deterministic outcome (either new action will be created or existing action will be reused in case CLS API tries to bind to action concurrently) due to idr lock serialization. We fix this by making refcount of newly created actions as 2 in ACT API replace mode. A relaxed store will suffice as visibility is ensured only after the tcf_idr_insert_many call. Note that in case of creation or overwriting using CLS API only (i.e. bind = 1), overwriting existing action object is not allowed, and any such request is silently ignored (without error). The refcount bump that occurs in tcf_idr_check_alloc call there for existing action will pair with tcf_exts_destroy call made from the owner module for the same action. In case of action creation, there is no existing action, so no tcf_exts_destroy callback happens. This means no code changes for CLS API. Fixes: cae422f379f3 ("net: sched: use reference counting action init") Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149 upstream.

Currently, action creation using ACT API in replace mode is buggy.
When invoking for non-existent action index 42,

	tc action replace action bpf obj foo.o sec <xyz> index 42

kernel creates the action, fills up the netlink response, and then just
deletes the action after notifying userspace.

	tc action show action bpf

doesn't list the action.

This happens due to the following sequence when ovr = 1 (replace mode)
is enabled:

tcf_idr_check_alloc is used to atomically check and either obtain
reference for existing action at index, or reserve the index slot using
a dummy entry (ERR_PTR(-EBUSY)).

This is necessary as pointers to these actions will be held after
dropping the idrinfo lock, so bumping the reference count is necessary
as we need to insert the actions, and notify userspace by dumping their
attributes. Finally, we drop the reference we took using the
tcf_action_put_many call in tcf_action_add. However, for the case where
a new action is created due to free index, its refcount remains one.
This when paired with the put_many call leads to the kernel setting up
the action, notifying userspace of its creation, and then tearing it
down. For existing actions, the refcount is still held so they remain
unaffected.

Fortunately due to rtnl_lock serialization requirement, such an action
with refcount == 1 will not be concurrently deleted by anything else, at
best CLS API can move its refcount up and down by binding to it after it
has been published from tcf_idr_insert_many. Since refcount is atleast
one until put_many call, CLS API cannot delete it. Also __tcf_action_put
release path already ensures deterministic outcome (either new action
will be created or existing action will be reused in case CLS API tries
to bind to action concurrently) due to idr lock serialization.

We fix this by making refcount of newly created actions as 2 in ACT API
replace mode. A relaxed store will suffice as visibility is ensured only
after the tcf_idr_insert_many call.

Note that in case of creation or overwriting using CLS API only (i.e.
bind = 1), overwriting existing action object is not allowed, and any
such request is silently ignored (without error).

The refcount bump that occurs in tcf_idr_check_alloc call there for
existing action will pair with tcf_exts_destroy call made from the
owner module for the same action. In case of action creation, there
is no existing action, so no tcf_exts_destroy callback happens.

This means no code changes for CLS API.

Fixes: cae422f379f3 ("net: sched: use reference counting action init")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: sched: fix err handler in tcf_action_init() 2021-04-14T06:42:05+00:00 Vlad Buslov vladbu@nvidia.com 2021-04-07T15:36:04+00:00 4a78ae12780394cae396ef4e8e94252271363363 [ Upstream commit b3650bf76a32380d4d80a3e21b5583e7303f216c ] With recent changes that separated action module load from action initialization tcf_action_init() function error handling code was modified to manually release the loaded modules if loading/initialization of any further action in same batch failed. For the case when all modules successfully loaded and some of the actions were initialized before one of them failed in init handler. In this case for all previous actions the module will be released twice by the error handler: First time by the loop that manually calls module_put() for all ops, and second time by the action destroy code that puts the module after destroying the action. Reproduction: $ sudo tc actions add action simple sdata \"2\" index 2 $ sudo tc actions add action simple sdata \"1\" index 1 \ action simple sdata \"2\" index 2 RTNETLINK answers: File exists We have an error talking to the kernel $ sudo tc actions ls action simple total acts 1 action order 0: Simple <"2"> index 2 ref 1 bind 0 $ sudo tc actions flush action simple $ sudo tc actions ls action simple $ sudo tc actions add action simple sdata \"2\" index 2 Error: Failed to load TC action module. We have an error talking to the kernel $ lsmod | grep simple act_simple 20480 -1 Fix the issue by modifying module reference counting handling in action initialization code: - Get module reference in tcf_idr_create() and put it in tcf_idr_release() instead of taking over the reference held by the caller. - Modify users of tcf_action_init_1() to always release the module reference which they obtain before calling init function instead of assuming that created action takes over the reference. - Finally, modify tcf_action_init_1() to not release the module reference when overwriting existing action as this is no longer necessary since both upper and lower layers obtain and manage their own module references independently. Fixes: d349f9976868 ("net_sched: fix RTNL deadlock again caused by request_module()") Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Vlad Buslov <vladbu@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b3650bf76a32380d4d80a3e21b5583e7303f216c ]

With recent changes that separated action module load from action
initialization tcf_action_init() function error handling code was modified
to manually release the loaded modules if loading/initialization of any
further action in same batch failed. For the case when all modules
successfully loaded and some of the actions were initialized before one of
them failed in init handler. In this case for all previous actions the
module will be released twice by the error handler: First time by the loop
that manually calls module_put() for all ops, and second time by the action
destroy code that puts the module after destroying the action.

Reproduction:

$ sudo tc actions add action simple sdata \"2\" index 2
$ sudo tc actions add action simple sdata \"1\" index 1 \
                      action simple sdata \"2\" index 2
RTNETLINK answers: File exists
We have an error talking to the kernel
$ sudo tc actions ls action simple
total acts 1

        action order 0: Simple <"2">
         index 2 ref 1 bind 0
$ sudo tc actions flush action simple
$ sudo tc actions ls action simple
$ sudo tc actions add action simple sdata \"2\" index 2
Error: Failed to load TC action module.
We have an error talking to the kernel
$ lsmod | grep simple
act_simple             20480  -1

Fix the issue by modifying module reference counting handling in action
initialization code:

- Get module reference in tcf_idr_create() and put it in tcf_idr_release()
instead of taking over the reference held by the caller.

- Modify users of tcf_action_init_1() to always release the module
reference which they obtain before calling init function instead of
assuming that created action takes over the reference.

- Finally, modify tcf_action_init_1() to not release the module reference
when overwriting existing action as this is no longer necessary since both
upper and lower layers obtain and manage their own module references
independently.

Fixes: d349f9976868 ("net_sched: fix RTNL deadlock again caused by request_module()")
Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: sched: fix action overwrite reference counting 2021-04-14T06:42:02+00:00 Vlad Buslov vladbu@nvidia.com 2021-04-07T15:36:03+00:00 81692c6add7e55309bdc275f59301efd4b49e958 commit 87c750e8c38bce706eb32e4d8f1e3402f2cebbd4 upstream. Action init code increments reference counter when it changes an action. This is the desired behavior for cls API which needs to obtain action reference for every classifier that points to action. However, act API just needs to change the action and releases the reference before returning. This sequence breaks when the requested action doesn't exist, which causes act API init code to create new action with specified index, but action is still released before returning and is deleted (unless it was referenced concurrently by cls API). Reproduction: $ sudo tc actions ls action gact $ sudo tc actions change action gact drop index 1 $ sudo tc actions ls action gact Extend tcf_action_init() to accept 'init_res' array and initialize it with action->ops->init() result. In tcf_action_add() remove pointers to created actions from actions array before passing it to tcf_action_put_many(). Fixes: cae422f379f3 ("net: sched: use reference counting action init") Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Vlad Buslov <vladbu@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 87c750e8c38bce706eb32e4d8f1e3402f2cebbd4 upstream.

Action init code increments reference counter when it changes an action.
This is the desired behavior for cls API which needs to obtain action
reference for every classifier that points to action. However, act API just
needs to change the action and releases the reference before returning.
This sequence breaks when the requested action doesn't exist, which causes
act API init code to create new action with specified index, but action is
still released before returning and is deleted (unless it was referenced
concurrently by cls API).

Reproduction:

$ sudo tc actions ls action gact
$ sudo tc actions change action gact drop index 1
$ sudo tc actions ls action gact

Extend tcf_action_init() to accept 'init_res' array and initialize it with
action->ops->init() result. In tcf_action_add() remove pointers to created
actions from actions array before passing it to tcf_action_put_many().

Fixes: cae422f379f3 ("net: sched: use reference counting action init")
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net_sched: fix RTNL deadlock again caused by request_module() 2021-03-04T10:38:47+00:00 Cong Wang cong.wang@bytedance.com 2021-01-17T00:56:57+00:00 a3b6f3a3758ead2092fa6b68e7063491e973b3f9 commit d349f997686887906b1183b5be96933c5452362a upstream. tcf_action_init_1() loads tc action modules automatically with request_module() after parsing the tc action names, and it drops RTNL lock and re-holds it before and after request_module(). This causes a lot of troubles, as discovered by syzbot, because we can be in the middle of batch initializations when we create an array of tc actions. One of the problem is deadlock: CPU 0 CPU 1 rtnl_lock(); for (...) { tcf_action_init_1(); -> rtnl_unlock(); -> request_module(); rtnl_lock(); for (...) { tcf_action_init_1(); -> tcf_idr_check_alloc(); // Insert one action into idr, // but it is not committed until // tcf_idr_insert_many(), then drop // the RTNL lock in the _next_ // iteration -> rtnl_unlock(); -> rtnl_lock(); -> a_o->init(); -> tcf_idr_check_alloc(); // Now waiting for the same index // to be committed -> request_module(); -> rtnl_lock() // Now waiting for RTNL lock } rtnl_unlock(); } rtnl_unlock(); This is not easy to solve, we can move the request_module() before this loop and pre-load all the modules we need for this netlink message and then do the rest initializations. So the loop breaks down to two now: for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { struct tc_action_ops *a_o; a_o = tc_action_load_ops(name, tb[i]...); ops[i - 1] = a_o; } for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { act = tcf_action_init_1(ops[i - 1]...); } Although this looks serious, it only has been reported by syzbot, so it seems hard to trigger this by humans. And given the size of this patch, I'd suggest to make it to net-next and not to backport to stable. This patch has been tested by syzbot and tested with tdc.py by me. Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together") Reported-and-tested-by: syzbot+82752bc5331601cf4899@syzkaller.appspotmail.com Reported-and-tested-by: syzbot+b3b63b6bff456bd95294@syzkaller.appspotmail.com Reported-by: syzbot+ba67b12b1ca729912834@syzkaller.appspotmail.com Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Cong Wang <cong.wang@bytedance.com> Tested-by: Jamal Hadi Salim <jhs@mojatatu.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20210117005657.14810-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d349f997686887906b1183b5be96933c5452362a upstream.

tcf_action_init_1() loads tc action modules automatically with
request_module() after parsing the tc action names, and it drops RTNL
lock and re-holds it before and after request_module(). This causes a
lot of troubles, as discovered by syzbot, because we can be in the
middle of batch initializations when we create an array of tc actions.

One of the problem is deadlock:

CPU 0					CPU 1
rtnl_lock();
for (...) {
  tcf_action_init_1();
    -> rtnl_unlock();
    -> request_module();
				rtnl_lock();
				for (...) {
				  tcf_action_init_1();
				    -> tcf_idr_check_alloc();
				   // Insert one action into idr,
				   // but it is not committed until
				   // tcf_idr_insert_many(), then drop
				   // the RTNL lock in the _next_
				   // iteration
				   -> rtnl_unlock();
    -> rtnl_lock();
    -> a_o->init();
      -> tcf_idr_check_alloc();
      // Now waiting for the same index
      // to be committed
				    -> request_module();
				    -> rtnl_lock()
				    // Now waiting for RTNL lock
				}
				rtnl_unlock();
}
rtnl_unlock();

This is not easy to solve, we can move the request_module() before
this loop and pre-load all the modules we need for this netlink
message and then do the rest initializations. So the loop breaks down
to two now:

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                struct tc_action_ops *a_o;

                a_o = tc_action_load_ops(name, tb[i]...);
                ops[i - 1] = a_o;
        }

        for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) {
                act = tcf_action_init_1(ops[i - 1]...);
        }

Although this looks serious, it only has been reported by syzbot, so it
seems hard to trigger this by humans. And given the size of this patch,
I'd suggest to make it to net-next and not to backport to stable.

This patch has been tested by syzbot and tested with tdc.py by me.

Fixes: 0fedc63fadf0 ("net_sched: commit action insertions together")
Reported-and-tested-by: syzbot+82752bc5331601cf4899@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+b3b63b6bff456bd95294@syzkaller.appspotmail.com
Reported-by: syzbot+ba67b12b1ca729912834@syzkaller.appspotmail.com
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Tested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20210117005657.14810-1-xiyou.wangcong@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>