linux.git/fs/tracefs, branch v6.6.131 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git tracefs: fix a leak in eventfs_create_events_dir() 2026-01-11T14:21:25+00:00 Al Viro viro@zeniv.linux.org.uk 2025-10-25T22:13:48+00:00 07a0310292011a1dde9ad93250203783b6b58b70 [ Upstream commit 798a401660a151633cb171738a72a8f1efb9b0b4 ] If we have LOCKDOWN_TRACEFS, the function bails out - *after* having locked the parent directory and without bothering to undo that. Just check it before tracefs_start_creating()... Fixes: e24709454c45 "tracefs/eventfs: Add missing lockdown checks" Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 798a401660a151633cb171738a72a8f1efb9b0b4 ]

If we have LOCKDOWN_TRACEFS, the function bails out - *after*
having locked the parent directory and without bothering to
undo that.  Just check it before tracefs_start_creating()...

Fixes: e24709454c45 "tracefs/eventfs: Add missing lockdown checks"
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tracefs: Add d_delete to remove negative dentries 2025-08-28T14:28:15+00:00 Steven Rostedt rostedt@goodmis.org 2025-06-11T16:18:15+00:00 839312bff2c95a879a63fba150ad820b13a5dfdd [ Upstream commit d9b13cdad80dc11d74408cf201939a946e9303a6 ] If a lookup in tracefs is done on a file that does not exist, it leaves a dentry hanging around until memory pressure removes it. But eventfs dentries should hang around as when their ref count goes to zero, it requires more work to recreate it. For the rest of the tracefs dentries, they hang around as their dentry is used as a descriptor for the tracing system. But if a file lookup happens for a file in tracefs that does not exist, it should be deleted. Add a .d_delete callback that checks if dentry->fsdata is set or not. Only eventfs dentries set fsdata so if it has content it should not be deleted and should hang around in the cache. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d9b13cdad80dc11d74408cf201939a946e9303a6 ]

If a lookup in tracefs is done on a file that does not exist, it leaves a
dentry hanging around until memory pressure removes it. But eventfs
dentries should hang around as when their ref count goes to zero, it
requires more work to recreate it. For the rest of the tracefs dentries,
they hang around as their dentry is used as a descriptor for the tracing
system. But if a file lookup happens for a file in tracefs that does not
exist, it should be deleted.

Add a .d_delete callback that checks if dentry->fsdata is set or not. Only
eventfs dentries set fsdata so if it has content it should not be deleted
and should hang around in the cache.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
eventfs: Use list_del_rcu() for SRCU protected list variable 2024-09-12T09:11:27+00:00 Steven Rostedt rostedt@goodmis.org 2024-09-04T17:16:05+00:00 05e08297c3c298d8ec28e5a5adb55840312dd87e commit d2603279c7d645bf0d11fa253b23f1ab48fc8d3c upstream. Chi Zhiling reported: We found a null pointer accessing in tracefs[1], the reason is that the variable 'ei_child' is set to LIST_POISON1, that means the list was removed in eventfs_remove_rec. so when access the ei_child->is_freed, the panic triggered. by the way, the following script can reproduce this panic loop1 (){ while true do echo "p:kp submit_bio" > /sys/kernel/debug/tracing/kprobe_events echo "" > /sys/kernel/debug/tracing/kprobe_events done } loop2 (){ while true do tree /sys/kernel/debug/tracing/events/kprobes/ done } loop1 & loop2 [1]: [ 1147.959632][T17331] Unable to handle kernel paging request at virtual address dead000000000150 [ 1147.968239][T17331] Mem abort info: [ 1147.971739][T17331] ESR = 0x0000000096000004 [ 1147.976172][T17331] EC = 0x25: DABT (current EL), IL = 32 bits [ 1147.982171][T17331] SET = 0, FnV = 0 [ 1147.985906][T17331] EA = 0, S1PTW = 0 [ 1147.989734][T17331] FSC = 0x04: level 0 translation fault [ 1147.995292][T17331] Data abort info: [ 1147.998858][T17331] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 1148.005023][T17331] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 1148.010759][T17331] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 1148.016752][T17331] [dead000000000150] address between user and kernel address ranges [ 1148.024571][T17331] Internal error: Oops: 0000000096000004 [#1] SMP [ 1148.030825][T17331] Modules linked in: team_mode_loadbalance team nlmon act_gact cls_flower sch_ingress bonding tls macvlan dummy ib_core bridge stp llc veth amdgpu amdxcp mfd_core gpu_sched drm_exec drm_buddy radeon crct10dif_ce video drm_suballoc_helper ghash_ce drm_ttm_helper sha2_ce ttm sha256_arm64 i2c_algo_bit sha1_ce sbsa_gwdt cp210x drm_display_helper cec sr_mod cdrom drm_kms_helper binfmt_misc sg loop fuse drm dm_mod nfnetlink ip_tables autofs4 [last unloaded: tls] [ 1148.072808][T17331] CPU: 3 PID: 17331 Comm: ls Tainted: G W ------- ---- 6.6.43 #2 [ 1148.081751][T17331] Source Version: 21b3b386e948bedd29369af66f3e98ab01b1c650 [ 1148.088783][T17331] Hardware name: Greatwall GW-001M1A-FTF/GW-001M1A-FTF, BIOS KunLun BIOS V4.0 07/16/2020 [ 1148.098419][T17331] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 1148.106060][T17331] pc : eventfs_iterate+0x2c0/0x398 [ 1148.111017][T17331] lr : eventfs_iterate+0x2fc/0x398 [ 1148.115969][T17331] sp : ffff80008d56bbd0 [ 1148.119964][T17331] x29: ffff80008d56bbf0 x28: ffff001ff5be2600 x27: 0000000000000000 [ 1148.127781][T17331] x26: ffff001ff52ca4e0 x25: 0000000000009977 x24: dead000000000100 [ 1148.135598][T17331] x23: 0000000000000000 x22: 000000000000000b x21: ffff800082645f10 [ 1148.143415][T17331] x20: ffff001fddf87c70 x19: ffff80008d56bc90 x18: 0000000000000000 [ 1148.151231][T17331] x17: 0000000000000000 x16: 0000000000000000 x15: ffff001ff52ca4e0 [ 1148.159048][T17331] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 [ 1148.166864][T17331] x11: 0000000000000000 x10: 0000000000000000 x9 : ffff8000804391d0 [ 1148.174680][T17331] x8 : 0000000180000000 x7 : 0000000000000018 x6 : 0000aaab04b92862 [ 1148.182498][T17331] x5 : 0000aaab04b92862 x4 : 0000000080000000 x3 : 0000000000000068 [ 1148.190314][T17331] x2 : 000000000000000f x1 : 0000000000007ea8 x0 : 0000000000000001 [ 1148.198131][T17331] Call trace: [ 1148.201259][T17331] eventfs_iterate+0x2c0/0x398 [ 1148.205864][T17331] iterate_dir+0x98/0x188 [ 1148.210036][T17331] __arm64_sys_getdents64+0x78/0x160 [ 1148.215161][T17331] invoke_syscall+0x78/0x108 [ 1148.219593][T17331] el0_svc_common.constprop.0+0x48/0xf0 [ 1148.224977][T17331] do_el0_svc+0x24/0x38 [ 1148.228974][T17331] el0_svc+0x40/0x168 [ 1148.232798][T17331] el0t_64_sync_handler+0x120/0x130 [ 1148.237836][T17331] el0t_64_sync+0x1a4/0x1a8 [ 1148.242182][T17331] Code: 54ffff6c f9400676 910006d6 f9000676 (b9405300) [ 1148.248955][T17331] ---[ end trace 0000000000000000 ]--- The issue is that list_del() is used on an SRCU protected list variable before the synchronization occurs. This can poison the list pointers while there is a reader iterating the list. This is simply fixed by using list_del_rcu() that is specifically made for this purpose. Link: https://lore.kernel.org/linux-trace-kernel/20240829085025.3600021-1-chizhiling@163.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20240904131605.640d42b1@gandalf.local.home Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcounts") Reported-by: Chi Zhiling <chizhiling@kylinos.cn> Tested-by: Chi Zhiling <chizhiling@kylinos.cn> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d2603279c7d645bf0d11fa253b23f1ab48fc8d3c upstream.

Chi Zhiling reported:

  We found a null pointer accessing in tracefs[1], the reason is that the
  variable 'ei_child' is set to LIST_POISON1, that means the list was
  removed in eventfs_remove_rec. so when access the ei_child->is_freed, the
  panic triggered.

  by the way, the following script can reproduce this panic

  loop1 (){
      while true
      do
          echo "p:kp submit_bio" > /sys/kernel/debug/tracing/kprobe_events
          echo "" > /sys/kernel/debug/tracing/kprobe_events
      done
  }
  loop2 (){
      while true
      do
          tree /sys/kernel/debug/tracing/events/kprobes/
      done
  }
  loop1 &
  loop2

  [1]:
  [ 1147.959632][T17331] Unable to handle kernel paging request at virtual address dead000000000150
  [ 1147.968239][T17331] Mem abort info:
  [ 1147.971739][T17331]   ESR = 0x0000000096000004
  [ 1147.976172][T17331]   EC = 0x25: DABT (current EL), IL = 32 bits
  [ 1147.982171][T17331]   SET = 0, FnV = 0
  [ 1147.985906][T17331]   EA = 0, S1PTW = 0
  [ 1147.989734][T17331]   FSC = 0x04: level 0 translation fault
  [ 1147.995292][T17331] Data abort info:
  [ 1147.998858][T17331]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
  [ 1148.005023][T17331]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  [ 1148.010759][T17331]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
  [ 1148.016752][T17331] [dead000000000150] address between user and kernel address ranges
  [ 1148.024571][T17331] Internal error: Oops: 0000000096000004 [#1] SMP
  [ 1148.030825][T17331] Modules linked in: team_mode_loadbalance team nlmon act_gact cls_flower sch_ingress bonding tls macvlan dummy ib_core bridge stp llc veth amdgpu amdxcp mfd_core gpu_sched drm_exec drm_buddy radeon crct10dif_ce video drm_suballoc_helper ghash_ce drm_ttm_helper sha2_ce ttm sha256_arm64 i2c_algo_bit sha1_ce sbsa_gwdt cp210x drm_display_helper cec sr_mod cdrom drm_kms_helper binfmt_misc sg loop fuse drm dm_mod nfnetlink ip_tables autofs4 [last unloaded: tls]
  [ 1148.072808][T17331] CPU: 3 PID: 17331 Comm: ls Tainted: G        W         ------- ----  6.6.43 #2
  [ 1148.081751][T17331] Source Version: 21b3b386e948bedd29369af66f3e98ab01b1c650
  [ 1148.088783][T17331] Hardware name: Greatwall GW-001M1A-FTF/GW-001M1A-FTF, BIOS KunLun BIOS V4.0 07/16/2020
  [ 1148.098419][T17331] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  [ 1148.106060][T17331] pc : eventfs_iterate+0x2c0/0x398
  [ 1148.111017][T17331] lr : eventfs_iterate+0x2fc/0x398
  [ 1148.115969][T17331] sp : ffff80008d56bbd0
  [ 1148.119964][T17331] x29: ffff80008d56bbf0 x28: ffff001ff5be2600 x27: 0000000000000000
  [ 1148.127781][T17331] x26: ffff001ff52ca4e0 x25: 0000000000009977 x24: dead000000000100
  [ 1148.135598][T17331] x23: 0000000000000000 x22: 000000000000000b x21: ffff800082645f10
  [ 1148.143415][T17331] x20: ffff001fddf87c70 x19: ffff80008d56bc90 x18: 0000000000000000
  [ 1148.151231][T17331] x17: 0000000000000000 x16: 0000000000000000 x15: ffff001ff52ca4e0
  [ 1148.159048][T17331] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
  [ 1148.166864][T17331] x11: 0000000000000000 x10: 0000000000000000 x9 : ffff8000804391d0
  [ 1148.174680][T17331] x8 : 0000000180000000 x7 : 0000000000000018 x6 : 0000aaab04b92862
  [ 1148.182498][T17331] x5 : 0000aaab04b92862 x4 : 0000000080000000 x3 : 0000000000000068
  [ 1148.190314][T17331] x2 : 000000000000000f x1 : 0000000000007ea8 x0 : 0000000000000001
  [ 1148.198131][T17331] Call trace:
  [ 1148.201259][T17331]  eventfs_iterate+0x2c0/0x398
  [ 1148.205864][T17331]  iterate_dir+0x98/0x188
  [ 1148.210036][T17331]  __arm64_sys_getdents64+0x78/0x160
  [ 1148.215161][T17331]  invoke_syscall+0x78/0x108
  [ 1148.219593][T17331]  el0_svc_common.constprop.0+0x48/0xf0
  [ 1148.224977][T17331]  do_el0_svc+0x24/0x38
  [ 1148.228974][T17331]  el0_svc+0x40/0x168
  [ 1148.232798][T17331]  el0t_64_sync_handler+0x120/0x130
  [ 1148.237836][T17331]  el0t_64_sync+0x1a4/0x1a8
  [ 1148.242182][T17331] Code: 54ffff6c f9400676 910006d6 f9000676 (b9405300)
  [ 1148.248955][T17331] ---[ end trace 0000000000000000 ]---

The issue is that list_del() is used on an SRCU protected list variable
before the synchronization occurs. This can poison the list pointers while
there is a reader iterating the list.

This is simply fixed by using list_del_rcu() that is specifically made for
this purpose.

Link: https://lore.kernel.org/linux-trace-kernel/20240829085025.3600021-1-chizhiling@163.com/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20240904131605.640d42b1@gandalf.local.home
Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcounts")
Reported-by: Chi Zhiling <chizhiling@kylinos.cn>
Tested-by: Chi Zhiling <chizhiling@kylinos.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
eventfs: Use SRCU for freeing eventfs_inodes 2024-08-14T11:58:59+00:00 Mathias Krause minipli@grsecurity.net 2024-07-23T21:07:53+00:00 2ef3d120d19faba3dec35b10a025b00db0284373 commit 8e556432477e97ad6179c61b61a32bf5f1af2355 upstream. To mirror the SRCU lock held in eventfs_iterate() when iterating over eventfs inodes, use call_srcu() to free them too. This was accidentally(?) degraded to RCU in commit 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts"). Cc: Ajay Kaher <ajay.kaher@broadcom.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20240723210755.8970-1-minipli@grsecurity.net Fixes: 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts") Signed-off-by: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8e556432477e97ad6179c61b61a32bf5f1af2355 upstream.

To mirror the SRCU lock held in eventfs_iterate() when iterating over
eventfs inodes, use call_srcu() to free them too.

This was accidentally(?) degraded to RCU in commit 43aa6f97c2d0
("eventfs: Get rid of dentry pointers without refcounts").

Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20240723210755.8970-1-minipli@grsecurity.net
Fixes: 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts")
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
eventfs: Don't return NULL in eventfs_create_dir() 2024-08-14T11:58:59+00:00 Mathias Krause minipli@grsecurity.net 2024-07-23T12:25:21+00:00 b59603a114fa490503251e2182943ccf09c5f487 commit 12c20c65d0460cf34f9a665d8f0c0d77d45a3829 upstream. Commit 77a06c33a22d ("eventfs: Test for ei->is_freed when accessing ei->dentry") added another check, testing if the parent was freed after we released the mutex. If so, the function returns NULL. However, all callers expect it to either return a valid pointer or an error pointer, at least since commit 5264a2f4bb3b ("tracing: Fix a NULL vs IS_ERR() bug in event_subsystem_dir()"). Returning NULL will therefore fail the error condition check in the caller. Fix this by substituting the NULL return value with a fitting error pointer. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: stable@vger.kernel.org Fixes: 77a06c33a22d ("eventfs: Test for ei->is_freed when accessing ei->dentry") Link: https://lore.kernel.org/20240723122522.2724-1-minipli@grsecurity.net Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org> Reviewed-by: Ajay Kaher <ajay.kaher@broadcom.com> Signed-off-by: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 12c20c65d0460cf34f9a665d8f0c0d77d45a3829 upstream.

Commit 77a06c33a22d ("eventfs: Test for ei->is_freed when accessing
ei->dentry") added another check, testing if the parent was freed after
we released the mutex. If so, the function returns NULL. However, all
callers expect it to either return a valid pointer or an error pointer,
at least since commit 5264a2f4bb3b ("tracing: Fix a NULL vs IS_ERR() bug
in event_subsystem_dir()"). Returning NULL will therefore fail the error
condition check in the caller.

Fix this by substituting the NULL return value with a fitting error
pointer.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Fixes: 77a06c33a22d ("eventfs: Test for ei->is_freed when accessing ei->dentry")
Link: https://lore.kernel.org/20240723122522.2724-1-minipli@grsecurity.net
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Ajay Kaher <ajay.kaher@broadcom.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tracefs: Use generic inode RCU for synchronizing freeing 2024-08-14T11:58:56+00:00 Steven Rostedt rostedt@goodmis.org 2024-08-07T22:54:02+00:00 726f4c241e17be75a9cf6870d80cd7479dc89e8f commit 0b6743bd60a56a701070b89fb80c327a44b7b3e2 upstream. With structure layout randomization enabled for 'struct inode' we need to avoid overlapping any of the RCU-used / initialized-only-once members, e.g. i_lru or i_sb_list to not corrupt related list traversals when making use of the rcu_head. For an unlucky structure layout of 'struct inode' we may end up with the following splat when running the ftrace selftests: [<...>] list_del corruption, ffff888103ee2cb0->next (tracefs_inode_cache+0x0/0x4e0 [slab object]) is NULL (prev is tracefs_inode_cache+0x78/0x4e0 [slab object]) [<...>] ------------[ cut here ]------------ [<...>] kernel BUG at lib/list_debug.c:54! [<...>] invalid opcode: 0000 [#1] PREEMPT SMP KASAN [<...>] CPU: 3 PID: 2550 Comm: mount Tainted: G N 6.8.12-grsec+ #122 ed2f536ca62f28b087b90e3cc906a8d25b3ddc65 [<...>] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [<...>] RIP: 0010:[<ffffffff84656018>] __list_del_entry_valid_or_report+0x138/0x3e0 [<...>] Code: 48 b8 99 fb 65 f2 ff ff ff ff e9 03 5c d9 fc cc 48 b8 99 fb 65 f2 ff ff ff ff e9 33 5a d9 fc cc 48 b8 99 fb 65 f2 ff ff ff ff <0f> 0b 4c 89 e9 48 89 ea 48 89 ee 48 c7 c7 60 8f dd 89 31 c0 e8 2f [<...>] RSP: 0018:fffffe80416afaf0 EFLAGS: 00010283 [<...>] RAX: 0000000000000098 RBX: ffff888103ee2cb0 RCX: 0000000000000000 [<...>] RDX: ffffffff84655fe8 RSI: ffffffff89dd8b60 RDI: 0000000000000001 [<...>] RBP: ffff888103ee2cb0 R08: 0000000000000001 R09: fffffbd0082d5f25 [<...>] R10: fffffe80416af92f R11: 0000000000000001 R12: fdf99c16731d9b6d [<...>] R13: 0000000000000000 R14: ffff88819ad4b8b8 R15: 0000000000000000 [<...>] RBX: tracefs_inode_cache+0x0/0x4e0 [slab object] [<...>] RDX: __list_del_entry_valid_or_report+0x108/0x3e0 [<...>] RSI: __func__.47+0x4340/0x4400 [<...>] RBP: tracefs_inode_cache+0x0/0x4e0 [slab object] [<...>] RSP: process kstack fffffe80416afaf0+0x7af0/0x8000 [mount 2550 2550] [<...>] R09: kasan shadow of process kstack fffffe80416af928+0x7928/0x8000 [mount 2550 2550] [<...>] R10: process kstack fffffe80416af92f+0x792f/0x8000 [mount 2550 2550] [<...>] R14: tracefs_inode_cache+0x78/0x4e0 [slab object] [<...>] FS: 00006dcb380c1840(0000) GS:ffff8881e0600000(0000) knlGS:0000000000000000 [<...>] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [<...>] CR2: 000076ab72b30e84 CR3: 000000000b088004 CR4: 0000000000360ef0 shadow CR4: 0000000000360ef0 [<...>] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [<...>] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [<...>] ASID: 0003 [<...>] Stack: [<...>] ffffffff818a2315 00000000f5c856ee ffffffff896f1840 ffff888103ee2cb0 [<...>] ffff88812b6b9750 0000000079d714b6 fffffbfff1e9280b ffffffff8f49405f [<...>] 0000000000000001 0000000000000000 ffff888104457280 ffffffff8248b392 [<...>] Call Trace: [<...>] <TASK> [<...>] [<ffffffff818a2315>] ? lock_release+0x175/0x380 fffffe80416afaf0 [<...>] [<ffffffff8248b392>] list_lru_del+0x152/0x740 fffffe80416afb48 [<...>] [<ffffffff8248ba93>] list_lru_del_obj+0x113/0x280 fffffe80416afb88 [<...>] [<ffffffff8940fd19>] ? _atomic_dec_and_lock+0x119/0x200 fffffe80416afb90 [<...>] [<ffffffff8295b244>] iput_final+0x1c4/0x9a0 fffffe80416afbb8 [<...>] [<ffffffff8293a52b>] dentry_unlink_inode+0x44b/0xaa0 fffffe80416afbf8 [<...>] [<ffffffff8293fefc>] __dentry_kill+0x23c/0xf00 fffffe80416afc40 [<...>] [<ffffffff8953a85f>] ? __this_cpu_preempt_check+0x1f/0xa0 fffffe80416afc48 [<...>] [<ffffffff82949ce5>] ? shrink_dentry_list+0x1c5/0x760 fffffe80416afc70 [<...>] [<ffffffff82949b71>] ? shrink_dentry_list+0x51/0x760 fffffe80416afc78 [<...>] [<ffffffff82949da8>] shrink_dentry_list+0x288/0x760 fffffe80416afc80 [<...>] [<ffffffff8294ae75>] shrink_dcache_sb+0x155/0x420 fffffe80416afcc8 [<...>] [<ffffffff8953a7c3>] ? debug_smp_processor_id+0x23/0xa0 fffffe80416afce0 [<...>] [<ffffffff8294ad20>] ? do_one_tree+0x140/0x140 fffffe80416afcf8 [<...>] [<ffffffff82997349>] ? do_remount+0x329/0xa00 fffffe80416afd18 [<...>] [<ffffffff83ebf7a1>] ? security_sb_remount+0x81/0x1c0 fffffe80416afd38 [<...>] [<ffffffff82892096>] reconfigure_super+0x856/0x14e0 fffffe80416afd70 [<...>] [<ffffffff815d1327>] ? ns_capable_common+0xe7/0x2a0 fffffe80416afd90 [<...>] [<ffffffff82997436>] do_remount+0x416/0xa00 fffffe80416afdd0 [<...>] [<ffffffff829b2ba4>] path_mount+0x5c4/0x900 fffffe80416afe28 [<...>] [<ffffffff829b25e0>] ? finish_automount+0x13a0/0x13a0 fffffe80416afe60 [<...>] [<ffffffff82903812>] ? user_path_at_empty+0xb2/0x140 fffffe80416afe88 [<...>] [<ffffffff829b2ff5>] do_mount+0x115/0x1c0 fffffe80416afeb8 [<...>] [<ffffffff829b2ee0>] ? path_mount+0x900/0x900 fffffe80416afed8 [<...>] [<ffffffff8272461c>] ? __kasan_check_write+0x1c/0xa0 fffffe80416afee0 [<...>] [<ffffffff829b31cf>] __do_sys_mount+0x12f/0x280 fffffe80416aff30 [<...>] [<ffffffff829b36cd>] __x64_sys_mount+0xcd/0x2e0 fffffe80416aff70 [<...>] [<ffffffff819f8818>] ? syscall_trace_enter+0x218/0x380 fffffe80416aff88 [<...>] [<ffffffff8111655e>] x64_sys_call+0x5d5e/0x6720 fffffe80416affa8 [<...>] [<ffffffff8952756d>] do_syscall_64+0xcd/0x3c0 fffffe80416affb8 [<...>] [<ffffffff8100119b>] entry_SYSCALL_64_safe_stack+0x4c/0x87 fffffe80416affe8 [<...>] </TASK> [<...>] <PTREGS> [<...>] RIP: 0033:[<00006dcb382ff66a>] vm_area_struct[mount 2550 2550 file 6dcb38225000-6dcb3837e000 22 55(read|exec|mayread|mayexec)]+0x0/0xb8 [userland map] [<...>] Code: 48 8b 0d 29 18 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f6 17 0d 00 f7 d8 64 89 01 48 [<...>] RSP: 002b:0000763d68192558 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 [<...>] RAX: ffffffffffffffda RBX: 00006dcb38433264 RCX: 00006dcb382ff66a [<...>] RDX: 000017c3e0d11210 RSI: 000017c3e0d1a5a0 RDI: 000017c3e0d1ae70 [<...>] RBP: 000017c3e0d10fb0 R08: 000017c3e0d11260 R09: 00006dcb383d1be0 [<...>] R10: 000000000020002e R11: 0000000000000246 R12: 0000000000000000 [<...>] R13: 000017c3e0d1ae70 R14: 000017c3e0d11210 R15: 000017c3e0d10fb0 [<...>] RBX: vm_area_struct[mount 2550 2550 file 6dcb38433000-6dcb38434000 5b 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] RCX: vm_area_struct[mount 2550 2550 file 6dcb38225000-6dcb3837e000 22 55(read|exec|mayread|mayexec)]+0x0/0xb8 [userland map] [<...>] RDX: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] RSI: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] RDI: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] RBP: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] RSP: vm_area_struct[mount 2550 2550 anon 763d68173000-763d68195000 7ffffffdd 100133(read|write|mayread|maywrite|growsdown|account)]+0x0/0xb8 [userland map] [<...>] R08: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] R09: vm_area_struct[mount 2550 2550 file 6dcb383d1000-6dcb383d3000 1cd 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] R13: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] R14: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] R15: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map] [<...>] </PTREGS> [<...>] Modules linked in: [<...>] ---[ end trace 0000000000000000 ]--- The list debug message as well as RBX's symbolic value point out that the object in question was allocated from 'tracefs_inode_cache' and that the list's '->next' member is at offset 0. Dumping the layout of the relevant parts of 'struct tracefs_inode' gives the following: struct tracefs_inode { union { struct inode { struct list_head { struct list_head * next; /* 0 8 */ struct list_head * prev; /* 8 8 */ } i_lru; [...] } vfs_inode; struct callback_head { void (*func)(struct callback_head *); /* 0 8 */ struct callback_head * next; /* 8 8 */ } rcu; }; [...] }; Above shows that 'vfs_inode.i_lru' overlaps with 'rcu' which will destroy the 'i_lru' list as soon as the 'rcu' member gets used, e.g. in call_rcu() or later when calling the RCU callback. This will disturb concurrent list traversals as well as object reuse which assumes these list heads will keep their integrity. For reproduction, the following diff manually overlays 'i_lru' with 'rcu' as, otherwise, one would require some good portion of luck for gambling an unlucky RANDSTRUCT seed: --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -629,6 +629,7 @@ struct inode { umode_t i_mode; unsigned short i_opflags; kuid_t i_uid; + struct list_head i_lru; /* inode LRU list */ kgid_t i_gid; unsigned int i_flags; @@ -690,7 +691,6 @@ struct inode { u16 i_wb_frn_avg_time; u16 i_wb_frn_history; #endif - struct list_head i_lru; /* inode LRU list */ struct list_head i_sb_list; struct list_head i_wb_list; /* backing dev writeback list */ union { The tracefs inode does not need to supply its own RCU delayed destruction of its inode. The inode code itself offers both a "destroy_inode()" callback that gets called when the last reference of the inode is released, and the "free_inode()" which is called after a RCU synchronization period from the "destroy_inode()". The tracefs code can unlink the inode from its list in the destroy_inode() callback, and the simply free it from the free_inode() callback. This should provide the same protection. Link: https://lore.kernel.org/all/20240807115143.45927-3-minipli@grsecurity.net/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Ajay Kaher <ajay.kaher@broadcom.com> Cc: Ilkka =?utf-8?b?TmF1bGFww6TDpA==?= <digirigawa@gmail.com> Link: https://lore.kernel.org/20240807185402.61410544@gandalf.local.home Fixes: baa23a8d4360 ("tracefs: Reset permissions on remount if permissions are options") Reported-by: Mathias Krause <minipli@grsecurity.net> Reported-by: Brad Spengler <spender@grsecurity.net> Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0b6743bd60a56a701070b89fb80c327a44b7b3e2 upstream.

With structure layout randomization enabled for 'struct inode' we need to
avoid overlapping any of the RCU-used / initialized-only-once members,
e.g. i_lru or i_sb_list to not corrupt related list traversals when making
use of the rcu_head.

For an unlucky structure layout of 'struct inode' we may end up with the
following splat when running the ftrace selftests:

[<...>] list_del corruption, ffff888103ee2cb0->next (tracefs_inode_cache+0x0/0x4e0 [slab object]) is NULL (prev is tracefs_inode_cache+0x78/0x4e0 [slab object])
[<...>] ------------[ cut here ]------------
[<...>] kernel BUG at lib/list_debug.c:54!
[<...>] invalid opcode: 0000 [#1] PREEMPT SMP KASAN
[<...>] CPU: 3 PID: 2550 Comm: mount Tainted: G                 N  6.8.12-grsec+ #122 ed2f536ca62f28b087b90e3cc906a8d25b3ddc65
[<...>] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
[<...>] RIP: 0010:[<ffffffff84656018>] __list_del_entry_valid_or_report+0x138/0x3e0
[<...>] Code: 48 b8 99 fb 65 f2 ff ff ff ff e9 03 5c d9 fc cc 48 b8 99 fb 65 f2 ff ff ff ff e9 33 5a d9 fc cc 48 b8 99 fb 65 f2 ff ff ff ff <0f> 0b 4c 89 e9 48 89 ea 48 89 ee 48 c7 c7 60 8f dd 89 31 c0 e8 2f
[<...>] RSP: 0018:fffffe80416afaf0 EFLAGS: 00010283
[<...>] RAX: 0000000000000098 RBX: ffff888103ee2cb0 RCX: 0000000000000000
[<...>] RDX: ffffffff84655fe8 RSI: ffffffff89dd8b60 RDI: 0000000000000001
[<...>] RBP: ffff888103ee2cb0 R08: 0000000000000001 R09: fffffbd0082d5f25
[<...>] R10: fffffe80416af92f R11: 0000000000000001 R12: fdf99c16731d9b6d
[<...>] R13: 0000000000000000 R14: ffff88819ad4b8b8 R15: 0000000000000000
[<...>] RBX: tracefs_inode_cache+0x0/0x4e0 [slab object]
[<...>] RDX: __list_del_entry_valid_or_report+0x108/0x3e0
[<...>] RSI: __func__.47+0x4340/0x4400
[<...>] RBP: tracefs_inode_cache+0x0/0x4e0 [slab object]
[<...>] RSP: process kstack fffffe80416afaf0+0x7af0/0x8000 [mount 2550 2550]
[<...>] R09: kasan shadow of process kstack fffffe80416af928+0x7928/0x8000 [mount 2550 2550]
[<...>] R10: process kstack fffffe80416af92f+0x792f/0x8000 [mount 2550 2550]
[<...>] R14: tracefs_inode_cache+0x78/0x4e0 [slab object]
[<...>] FS:  00006dcb380c1840(0000) GS:ffff8881e0600000(0000) knlGS:0000000000000000
[<...>] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[<...>] CR2: 000076ab72b30e84 CR3: 000000000b088004 CR4: 0000000000360ef0 shadow CR4: 0000000000360ef0
[<...>] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[<...>] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[<...>] ASID: 0003
[<...>] Stack:
[<...>]  ffffffff818a2315 00000000f5c856ee ffffffff896f1840 ffff888103ee2cb0
[<...>]  ffff88812b6b9750 0000000079d714b6 fffffbfff1e9280b ffffffff8f49405f
[<...>]  0000000000000001 0000000000000000 ffff888104457280 ffffffff8248b392
[<...>] Call Trace:
[<...>]  <TASK>
[<...>]  [<ffffffff818a2315>] ? lock_release+0x175/0x380 fffffe80416afaf0
[<...>]  [<ffffffff8248b392>] list_lru_del+0x152/0x740 fffffe80416afb48
[<...>]  [<ffffffff8248ba93>] list_lru_del_obj+0x113/0x280 fffffe80416afb88
[<...>]  [<ffffffff8940fd19>] ? _atomic_dec_and_lock+0x119/0x200 fffffe80416afb90
[<...>]  [<ffffffff8295b244>] iput_final+0x1c4/0x9a0 fffffe80416afbb8
[<...>]  [<ffffffff8293a52b>] dentry_unlink_inode+0x44b/0xaa0 fffffe80416afbf8
[<...>]  [<ffffffff8293fefc>] __dentry_kill+0x23c/0xf00 fffffe80416afc40
[<...>]  [<ffffffff8953a85f>] ? __this_cpu_preempt_check+0x1f/0xa0 fffffe80416afc48
[<...>]  [<ffffffff82949ce5>] ? shrink_dentry_list+0x1c5/0x760 fffffe80416afc70
[<...>]  [<ffffffff82949b71>] ? shrink_dentry_list+0x51/0x760 fffffe80416afc78
[<...>]  [<ffffffff82949da8>] shrink_dentry_list+0x288/0x760 fffffe80416afc80
[<...>]  [<ffffffff8294ae75>] shrink_dcache_sb+0x155/0x420 fffffe80416afcc8
[<...>]  [<ffffffff8953a7c3>] ? debug_smp_processor_id+0x23/0xa0 fffffe80416afce0
[<...>]  [<ffffffff8294ad20>] ? do_one_tree+0x140/0x140 fffffe80416afcf8
[<...>]  [<ffffffff82997349>] ? do_remount+0x329/0xa00 fffffe80416afd18
[<...>]  [<ffffffff83ebf7a1>] ? security_sb_remount+0x81/0x1c0 fffffe80416afd38
[<...>]  [<ffffffff82892096>] reconfigure_super+0x856/0x14e0 fffffe80416afd70
[<...>]  [<ffffffff815d1327>] ? ns_capable_common+0xe7/0x2a0 fffffe80416afd90
[<...>]  [<ffffffff82997436>] do_remount+0x416/0xa00 fffffe80416afdd0
[<...>]  [<ffffffff829b2ba4>] path_mount+0x5c4/0x900 fffffe80416afe28
[<...>]  [<ffffffff829b25e0>] ? finish_automount+0x13a0/0x13a0 fffffe80416afe60
[<...>]  [<ffffffff82903812>] ? user_path_at_empty+0xb2/0x140 fffffe80416afe88
[<...>]  [<ffffffff829b2ff5>] do_mount+0x115/0x1c0 fffffe80416afeb8
[<...>]  [<ffffffff829b2ee0>] ? path_mount+0x900/0x900 fffffe80416afed8
[<...>]  [<ffffffff8272461c>] ? __kasan_check_write+0x1c/0xa0 fffffe80416afee0
[<...>]  [<ffffffff829b31cf>] __do_sys_mount+0x12f/0x280 fffffe80416aff30
[<...>]  [<ffffffff829b36cd>] __x64_sys_mount+0xcd/0x2e0 fffffe80416aff70
[<...>]  [<ffffffff819f8818>] ? syscall_trace_enter+0x218/0x380 fffffe80416aff88
[<...>]  [<ffffffff8111655e>] x64_sys_call+0x5d5e/0x6720 fffffe80416affa8
[<...>]  [<ffffffff8952756d>] do_syscall_64+0xcd/0x3c0 fffffe80416affb8
[<...>]  [<ffffffff8100119b>] entry_SYSCALL_64_safe_stack+0x4c/0x87 fffffe80416affe8
[<...>]  </TASK>
[<...>]  <PTREGS>
[<...>] RIP: 0033:[<00006dcb382ff66a>] vm_area_struct[mount 2550 2550 file 6dcb38225000-6dcb3837e000 22 55(read|exec|mayread|mayexec)]+0x0/0xb8 [userland map]
[<...>] Code: 48 8b 0d 29 18 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f6 17 0d 00 f7 d8 64 89 01 48
[<...>] RSP: 002b:0000763d68192558 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
[<...>] RAX: ffffffffffffffda RBX: 00006dcb38433264 RCX: 00006dcb382ff66a
[<...>] RDX: 000017c3e0d11210 RSI: 000017c3e0d1a5a0 RDI: 000017c3e0d1ae70
[<...>] RBP: 000017c3e0d10fb0 R08: 000017c3e0d11260 R09: 00006dcb383d1be0
[<...>] R10: 000000000020002e R11: 0000000000000246 R12: 0000000000000000
[<...>] R13: 000017c3e0d1ae70 R14: 000017c3e0d11210 R15: 000017c3e0d10fb0
[<...>] RBX: vm_area_struct[mount 2550 2550 file 6dcb38433000-6dcb38434000 5b 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] RCX: vm_area_struct[mount 2550 2550 file 6dcb38225000-6dcb3837e000 22 55(read|exec|mayread|mayexec)]+0x0/0xb8 [userland map]
[<...>] RDX: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] RSI: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] RDI: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] RBP: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] RSP: vm_area_struct[mount 2550 2550 anon 763d68173000-763d68195000 7ffffffdd 100133(read|write|mayread|maywrite|growsdown|account)]+0x0/0xb8 [userland map]
[<...>] R08: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] R09: vm_area_struct[mount 2550 2550 file 6dcb383d1000-6dcb383d3000 1cd 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] R13: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] R14: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>] R15: vm_area_struct[mount 2550 2550 anon 17c3e0d0f000-17c3e0d31000 17c3e0d0f 100033(read|write|mayread|maywrite|account)]+0x0/0xb8 [userland map]
[<...>]  </PTREGS>
[<...>] Modules linked in:
[<...>] ---[ end trace 0000000000000000 ]---

The list debug message as well as RBX's symbolic value point out that the
object in question was allocated from 'tracefs_inode_cache' and that the
list's '->next' member is at offset 0. Dumping the layout of the relevant
parts of 'struct tracefs_inode' gives the following:

  struct tracefs_inode {
    union {
      struct inode {
        struct list_head {
          struct list_head * next;                    /*     0     8 */
          struct list_head * prev;                    /*     8     8 */
        } i_lru;
        [...]
      } vfs_inode;
      struct callback_head {
        void (*func)(struct callback_head *);         /*     0     8 */
        struct callback_head * next;                  /*     8     8 */
      } rcu;
    };
    [...]
  };

Above shows that 'vfs_inode.i_lru' overlaps with 'rcu' which will
destroy the 'i_lru' list as soon as the 'rcu' member gets used, e.g. in
call_rcu() or later when calling the RCU callback. This will disturb
concurrent list traversals as well as object reuse which assumes these
list heads will keep their integrity.

For reproduction, the following diff manually overlays 'i_lru' with
'rcu' as, otherwise, one would require some good portion of luck for
gambling an unlucky RANDSTRUCT seed:

  --- a/include/linux/fs.h
  +++ b/include/linux/fs.h
  @@ -629,6 +629,7 @@ struct inode {
   	umode_t			i_mode;
   	unsigned short		i_opflags;
   	kuid_t			i_uid;
  +	struct list_head	i_lru;		/* inode LRU list */
   	kgid_t			i_gid;
   	unsigned int		i_flags;

  @@ -690,7 +691,6 @@ struct inode {
   	u16			i_wb_frn_avg_time;
   	u16			i_wb_frn_history;
   #endif
  -	struct list_head	i_lru;		/* inode LRU list */
   	struct list_head	i_sb_list;
   	struct list_head	i_wb_list;	/* backing dev writeback list */
   	union {

The tracefs inode does not need to supply its own RCU delayed destruction
of its inode. The inode code itself offers both a "destroy_inode()"
callback that gets called when the last reference of the inode is
released, and the "free_inode()" which is called after a RCU
synchronization period from the "destroy_inode()".

The tracefs code can unlink the inode from its list in the destroy_inode()
callback, and the simply free it from the free_inode() callback. This
should provide the same protection.

Link: https://lore.kernel.org/all/20240807115143.45927-3-minipli@grsecurity.net/

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Ilkka =?utf-8?b?TmF1bGFww6TDpA==?= <digirigawa@gmail.com>
Link: https://lore.kernel.org/20240807185402.61410544@gandalf.local.home
Fixes: baa23a8d4360 ("tracefs: Reset permissions on remount if permissions are options")
Reported-by: Mathias Krause <minipli@grsecurity.net>
Reported-by: Brad Spengler <spender@grsecurity.net>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tracefs: Fix inode allocation 2024-08-14T11:58:56+00:00 Mathias Krause minipli@grsecurity.net 2024-08-07T11:51:38+00:00 a49f7de9b8e98a83d7a475528ec6dd7e51719a37 commit 0df2ac59bebfac221463ef57ed3554899b41d75f upstream. The leading comment above alloc_inode_sb() is pretty explicit about it: /* * This must be used for allocating filesystems specific inodes to set * up the inode reclaim context correctly. */ Switch tracefs over to alloc_inode_sb() to make sure inodes are properly linked. Cc: Ajay Kaher <ajay.kaher@broadcom.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20240807115143.45927-2-minipli@grsecurity.net Fixes: ba37ff75e04b ("eventfs: Implement tracefs_inode_cache") Signed-off-by: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0df2ac59bebfac221463ef57ed3554899b41d75f upstream.

The leading comment above alloc_inode_sb() is pretty explicit about it:

  /*
   * This must be used for allocating filesystems specific inodes to set
   * up the inode reclaim context correctly.
   */

Switch tracefs over to alloc_inode_sb() to make sure inodes are properly
linked.

Cc: Ajay Kaher <ajay.kaher@broadcom.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20240807115143.45927-2-minipli@grsecurity.net
Fixes: ba37ff75e04b ("eventfs: Implement tracefs_inode_cache")
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
eventfs: Update all the eventfs_inodes from the events descriptor 2024-06-21T12:38:22+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2024-05-23T05:14:28+00:00 7ec535ed8724d18ae4e714d2277a5b89450659d2 [ Upstream commit 340f0c7067a95281ad13734f8225f49c6cf52067 ] The change to update the permissions of the eventfs_inode had the misconception that using the tracefs_inode would find all the eventfs_inodes that have been updated and reset them on remount. The problem with this approach is that the eventfs_inodes are freed when they are no longer used (basically the reason the eventfs system exists). When they are freed, the updated eventfs_inodes are not reset on a remount because their tracefs_inodes have been freed. Instead, since the events directory eventfs_inode always has a tracefs_inode pointing to it (it is not freed when finished), and the events directory has a link to all its children, have the eventfs_remount() function only operate on the events eventfs_inode and have it descend into its children updating their uid and gids. Link: https://lore.kernel.org/all/CAK7LNARXgaWw3kH9JgrnH4vK6fr8LDkNKf3wq8NhMWJrVwJyVQ@mail.gmail.com/ Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.754424703@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options") Reported-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 340f0c7067a95281ad13734f8225f49c6cf52067 ]

The change to update the permissions of the eventfs_inode had the
misconception that using the tracefs_inode would find all the
eventfs_inodes that have been updated and reset them on remount.
The problem with this approach is that the eventfs_inodes are freed when
they are no longer used (basically the reason the eventfs system exists).
When they are freed, the updated eventfs_inodes are not reset on a remount
because their tracefs_inodes have been freed.

Instead, since the events directory eventfs_inode always has a
tracefs_inode pointing to it (it is not freed when finished), and the
events directory has a link to all its children, have the
eventfs_remount() function only operate on the events eventfs_inode and
have it descend into its children updating their uid and gids.

Link: https://lore.kernel.org/all/CAK7LNARXgaWw3kH9JgrnH4vK6fr8LDkNKf3wq8NhMWJrVwJyVQ@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.754424703@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options")
Reported-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tracefs: Clear EVENT_INODE flag in tracefs_drop_inode() 2024-06-16T11:47:48+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2024-05-23T05:14:29+00:00 e5104cbb146f0f68772b71158bb78fdd8c948aa0 commit 0bcfd9aa4dafa03b88d68bf66b694df2a3e76cf3 upstream. When the inode is being dropped from the dentry, the TRACEFS_EVENT_INODE flag needs to be cleared to prevent a remount from calling eventfs_remount() on the tracefs_inode private data. There's a race between the inode is dropped (and the dentry freed) to where the inode is actually freed. If a remount happens between the two, the eventfs_inode could be accessed after it is freed (only the dentry keeps a ref count on it). Currently the TRACEFS_EVENT_INODE flag is cleared from the dentry iput() function. But this is incorrect, as it is possible that the inode has another reference to it. The flag should only be cleared when the inode is really being dropped and has no more references. That happens in the drop_inode callback of the inode, as that gets called when the last reference of the inode is released. Remove the tracefs_d_iput() function and move its logic to the more appropriate tracefs_drop_inode() callback function. Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.908205106@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0bcfd9aa4dafa03b88d68bf66b694df2a3e76cf3 upstream.

When the inode is being dropped from the dentry, the TRACEFS_EVENT_INODE
flag needs to be cleared to prevent a remount from calling
eventfs_remount() on the tracefs_inode private data. There's a race
between the inode is dropped (and the dentry freed) to where the inode is
actually freed. If a remount happens between the two, the eventfs_inode
could be accessed after it is freed (only the dentry keeps a ref count on
it).

Currently the TRACEFS_EVENT_INODE flag is cleared from the dentry iput()
function. But this is incorrect, as it is possible that the inode has
another reference to it. The flag should only be cleared when the inode is
really being dropped and has no more references. That happens in the
drop_inode callback of the inode, as that gets called when the last
reference of the inode is released.

Remove the tracefs_d_iput() function and move its logic to the more
appropriate tracefs_drop_inode() callback function.

Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.908205106@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Fixes: baa23a8d4360d ("tracefs: Reset permissions on remount if permissions are options")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
eventfs: Keep the directories from having the same inode number as files 2024-06-16T11:47:47+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2024-05-23T05:14:26+00:00 4e84ead3f60a4b3b25e2486e5f8708186349d778 commit 8898e7f288c47d450a3cf1511c791a03550c0789 upstream. The directories require unique inode numbers but all the eventfs files have the same inode number. Prevent the directories from having the same inode numbers as the files as that can confuse some tooling. Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.428826685@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Fixes: 834bf76add3e6 ("eventfs: Save directory inodes in the eventfs_inode structure") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8898e7f288c47d450a3cf1511c791a03550c0789 upstream.

The directories require unique inode numbers but all the eventfs files
have the same inode number. Prevent the directories from having the same
inode numbers as the files as that can confuse some tooling.

Link: https://lore.kernel.org/linux-trace-kernel/20240523051539.428826685@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Fixes: 834bf76add3e6 ("eventfs: Save directory inodes in the eventfs_inode structure")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>