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[ Upstream commit 5afedf670caf30a2b5a52da96eb7eac7dee6a9c9 ]
There is an use-after-free problem triggered by following process:
P1(sda) P2(sdb)
echo 0 > /sys/block/sdb/trace/enable
blk_trace_remove_queue
synchronize_rcu
blk_trace_free
relay_close
rcu_read_lock
__blk_add_trace
trace_note_tsk
(Iterate running_trace_list)
relay_close_buf
relay_destroy_buf
kfree(buf)
trace_note(sdb's bt)
relay_reserve
buf->offset <- nullptr deference (use-after-free) !!!
rcu_read_unlock
[ 502.714379] BUG: kernel NULL pointer dereference, address:
0000000000000010
[ 502.715260] #PF: supervisor read access in kernel mode
[ 502.715903] #PF: error_code(0x0000) - not-present page
[ 502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0
[ 502.717252] Oops: 0000 [#1] SMP
[ 502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360
[ 502.732872] Call Trace:
[ 502.733193] __blk_add_trace.cold+0x137/0x1a3
[ 502.733734] blk_add_trace_rq+0x7b/0xd0
[ 502.734207] blk_add_trace_rq_issue+0x54/0xa0
[ 502.734755] blk_mq_start_request+0xde/0x1b0
[ 502.735287] scsi_queue_rq+0x528/0x1140
...
[ 502.742704] sg_new_write.isra.0+0x16e/0x3e0
[ 502.747501] sg_ioctl+0x466/0x1100
Reproduce method:
ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])
ioctl(/dev/sda, BLKTRACESTART)
ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])
ioctl(/dev/sdb, BLKTRACESTART)
echo 0 > /sys/block/sdb/trace/enable &
// Add delay(mdelay/msleep) before kernel enters blk_trace_free()
ioctl$SG_IO(/dev/sda, SG_IO, ...)
// Enters trace_note_tsk() after blk_trace_free() returned
// Use mdelay in rcu region rather than msleep(which may schedule out)
Remove blk_trace from running_list before calling blk_trace_free() by
sysfs if blk_trace is at Blktrace_running state.
Fixes: c71a896154119f ("blktrace: add ftrace plugin")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20210923134921.109194-1-chengzhihao1@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 6fe7c745f2acb73e4cc961d7f91125eef5a8861f ]
Fixes a build error when CONFIG_HIST_TRIGGERS=n with boot-time
tracing. Since the trigger_process_regex() is defined only
when CONFIG_HIST_TRIGGERS=y, if it is disabled, the 'actions'
event option also must be disabled.
Link: https://lkml.kernel.org/r/162856123376.203126.582144262622247352.stgit@devnote2
Fixes: 81a59555ff15 ("tracing/boot: Add per-event settings")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 8e242060c6a4947e8ae7d29794af6a581db08841 ]
Since kprobe_events and uprobe_events only check whether the
other same-type probe event has the same name or not, if the
user gives the same name of the existing tracepoint event (or
the other type of probe events), it silently fails to create
the tracefs entry (but registered.) as below.
/sys/kernel/tracing # ls events/task/task_rename
enable filter format hist id trigger
/sys/kernel/tracing # echo p:task/task_rename vfs_read >> kprobe_events
[ 113.048508] Could not create tracefs 'task_rename' directory
/sys/kernel/tracing # cat kprobe_events
p:task/task_rename vfs_read
To fix this issue, check whether the existing events have the
same name or not in trace_probe_register_event_call(). If exists,
it rejects to register the new event.
Link: https://lkml.kernel.org/r/162936876189.187130.17558311387542061930.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 5acce0bff2a0420ce87d4591daeb867f47d552c2 ]
The following commands:
# echo 'read_max u64 size;' > synthetic_events
# echo 'hist:keys=common_pid:count=count:onmax($count).trace(read_max,count)' > events/syscalls/sys_enter_read/trigger
Causes:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 4 PID: 1763 Comm: bash Not tainted 5.14.0-rc2-test+ #155
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
RIP: 0010:strcmp+0xc/0x20
Code: 75 f7 31 c0 0f b6 0c 06 88 0c 02 48 83 c0 01 84 c9 75 f1 4c 89 c0
c3 0f 1f 80 00 00 00 00 31 c0 eb 08 48 83 c0 01 84 d2 74 0f <0f> b6 14 07
3a 14 06 74 ef 19 c0 83 c8 01 c3 31 c0 c3 66 90 48 89
RSP: 0018:ffffb5fdc0963ca8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffffb3a4e040 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff9714c0d0b640 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00000022986b7cde R09: ffffffffb3a4dff8
R10: 0000000000000000 R11: 0000000000000000 R12: ffff9714c50603c8
R13: 0000000000000000 R14: ffff97143fdf9e48 R15: ffff9714c01a2210
FS: 00007f1fa6785740(0000) GS:ffff9714da400000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000002d863004 CR4: 00000000001706e0
Call Trace:
__find_event_file+0x4e/0x80
action_create+0x6b7/0xeb0
? kstrdup+0x44/0x60
event_hist_trigger_func+0x1a07/0x2130
trigger_process_regex+0xbd/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xe9/0x310
ksys_write+0x68/0xe0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f1fa6879e87
The problem was the "trace(read_max,count)" where the "count" should be
"$count" as "onmax()" only handles variables (although it really should be
able to figure out that "count" is a field of sys_enter_read). But there's
a path that does not find the variable and ends up passing a NULL for the
event, which ends up getting passed to "strcmp()".
Add a check for NULL to return and error on the command with:
# cat error_log
hist:syscalls:sys_enter_read: error: Couldn't create or find variable
Command: hist:keys=common_pid:count=count:onmax($count).trace(read_max,count)
^
Link: https://lkml.kernel.org/r/20210808003011.4037f8d0@oasis.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 50450603ec9cb tracing: Add 'onmax' hist trigger action support
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 51e1bb9eeaf7868db56e58f47848e364ab4c4129 upstream.
Back then, commit 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper
to be called in tracers") added the bpf_probe_write_user() helper in order
to allow to override user space memory. Its original goal was to have a
facility to "debug, divert, and manipulate execution of semi-cooperative
processes" under CAP_SYS_ADMIN. Write to kernel was explicitly disallowed
since it would otherwise tamper with its integrity.
One use case was shown in cf9b1199de27 ("samples/bpf: Add test/example of
using bpf_probe_write_user bpf helper") where the program DNATs traffic
at the time of connect(2) syscall, meaning, it rewrites the arguments to
a syscall while they're still in userspace, and before the syscall has a
chance to copy the argument into kernel space. These days we have better
mechanisms in BPF for achieving the same (e.g. for load-balancers), but
without having to write to userspace memory.
Of course the bpf_probe_write_user() helper can also be used to abuse
many other things for both good or bad purpose. Outside of BPF, there is
a similar mechanism for ptrace(2) such as PTRACE_PEEK{TEXT,DATA} and
PTRACE_POKE{TEXT,DATA}, but would likely require some more effort.
Commit 96ae52279594 explicitly dedicated the helper for experimentation
purpose only. Thus, move the helper's availability behind a newly added
LOCKDOWN_BPF_WRITE_USER lockdown knob so that the helper is disabled under
the "integrity" mode. More fine-grained control can be implemented also
from LSM side with this change.
Fixes: 96ae52279594 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ff41c28c4b54052942180d8b3f49e75f1445135a upstream.
The event_trace_add_tracer() can fail. In this case, it leads to a crash
in start_creating with below call stack. Handle the error scenario
properly in trace_array_create_dir.
Call trace:
down_write+0x7c/0x204
start_creating.25017+0x6c/0x194
tracefs_create_file+0xc4/0x2b4
init_tracer_tracefs+0x5c/0x940
trace_array_create_dir+0x58/0xb4
trace_array_create+0x1bc/0x2b8
trace_array_get_by_name+0xdc/0x18c
Link: https://lkml.kernel.org/r/1627651386-21315-1-git-send-email-kamaagra@codeaurora.org
Cc: stable@vger.kernel.org
Fixes: 4114fbfd02f1 ("tracing: Enable creating new instance early boot")
Signed-off-by: Kamal Agrawal <kamaagra@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a9d10ca4986571bffc19778742d508cc8dd13e02 upstream.
Since the string type can not be the target of the addition / subtraction
operation, it must be rejected. Without this fix, the string type silently
converted to digits.
Link: https://lkml.kernel.org/r/162742654278.290973.1523000673366456634.stgit@devnote2
Cc: stable@vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2c05caa7ba8803209769b9e4fe02c38d77ae88d0 upstream.
When working on my user space applications, I found a bug in the synthetic
event code where the automated synthetic event field was not matching the
event field calculation it was attached to. Looking deeper into it, it was
because the calculation hist_field was not given a size.
The synthetic event fields are matched to their hist_fields either by
having the field have an identical string type, or if that does not match,
then the size and signed values are used to match the fields.
The problem arose when I tried to match a calculation where the fields
were "unsigned int". My tool created a synthetic event of type "u32". But
it failed to match. The string was:
diff=field1-field2:onmatch(event).trace(synth,$diff)
Adding debugging into the kernel, I found that the size of "diff" was 0.
And since it was given "unsigned int" as a type, the histogram fallback
code used size and signed. The signed matched, but the size of u32 (4) did
not match zero, and the event failed to be created.
This can be worse if the field you want to match is not one of the
acceptable fields for a synthetic event. As event fields can have any type
that is supported in Linux, this can cause an issue. For example, if a
type is an enum. Then there's no way to use that with any calculations.
Have the calculation field simply take on the size of what it is
calculating.
Link: https://lkml.kernel.org/r/20210730171951.59c7743f@oasis.local.home
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3b13911a2fd0dd0146c9777a254840c5466cf120 upstream.
Performing the following:
># echo 'wakeup_lat s32 pid; u64 delta; char wake_comm[]' > synthetic_events
># echo 'hist:keys=pid:__arg__1=common_timestamp.usecs' > events/sched/sched_waking/trigger
># echo 'hist:keys=next_pid:pid=next_pid,delta=common_timestamp.usecs-$__arg__1:onmatch(sched.sched_waking).trace(wakeup_lat,$pid,$delta,prev_comm)'\
> events/sched/sched_switch/trigger
># echo 1 > events/synthetic/enable
Crashed the kernel:
BUG: kernel NULL pointer dereference, address: 000000000000001b
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 7 PID: 0 Comm: swapper/7 Not tainted 5.13.0-rc5-test+ #104
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
RIP: 0010:strlen+0x0/0x20
Code: f6 82 80 2b 0b bc 20 74 11 0f b6 50 01 48 83 c0 01 f6 82 80 2b 0b bc
20 75 ef c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <80> 3f 00 74 10
48 89 f8 48 83 c0 01 80 38 9 f8 c3 31
RSP: 0018:ffffaa75000d79d0 EFLAGS: 00010046
RAX: 0000000000000002 RBX: ffff9cdb55575270 RCX: 0000000000000000
RDX: ffff9cdb58c7a320 RSI: ffffaa75000d7b40 RDI: 000000000000001b
RBP: ffffaa75000d7b40 R08: ffff9cdb40a4f010 R09: ffffaa75000d7ab8
R10: ffff9cdb4398c700 R11: 0000000000000008 R12: ffff9cdb58c7a320
R13: ffff9cdb55575270 R14: ffff9cdb58c7a000 R15: 0000000000000018
FS: 0000000000000000(0000) GS:ffff9cdb5aa00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000001b CR3: 00000000c0612006 CR4: 00000000001706e0
Call Trace:
trace_event_raw_event_synth+0x90/0x1d0
action_trace+0x5b/0x70
event_hist_trigger+0x4bd/0x4e0
? cpumask_next_and+0x20/0x30
? update_sd_lb_stats.constprop.0+0xf6/0x840
? __lock_acquire.constprop.0+0x125/0x550
? find_held_lock+0x32/0x90
? sched_clock_cpu+0xe/0xd0
? lock_release+0x155/0x440
? update_load_avg+0x8c/0x6f0
? enqueue_entity+0x18a/0x920
? __rb_reserve_next+0xe5/0x460
? ring_buffer_lock_reserve+0x12a/0x3f0
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x1ae/0x240
trace_event_raw_event_sched_switch+0x114/0x170
__traceiter_sched_switch+0x39/0x50
__schedule+0x431/0xb00
schedule_idle+0x28/0x40
do_idle+0x198/0x2e0
cpu_startup_entry+0x19/0x20
secondary_startup_64_no_verify+0xc2/0xcb
The reason is that the dynamic events array keeps track of the field
position of the fields array, via the field_pos variable in the
synth_field structure. Unfortunately, that field is a boolean for some
reason, which means any field_pos greater than 1 will be a bug (in this
case it was 2).
Link: https://lkml.kernel.org/r/20210721191008.638bce34@oasis.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 67f0d6d9883c13174669f88adac4f0ee656cc16a upstream.
The "rb_per_cpu_empty()" misinterpret the condition (as not-empty) when
"head_page" and "commit_page" of "struct ring_buffer_per_cpu" points to
the same buffer page, whose "buffer_data_page" is empty and "read" field
is non-zero.
An error scenario could be constructed as followed (kernel perspective):
1. All pages in the buffer has been accessed by reader(s) so that all of
them will have non-zero "read" field.
2. Read and clear all buffer pages so that "rb_num_of_entries()" will
return 0 rendering there's no more data to read. It is also required
that the "read_page", "commit_page" and "tail_page" points to the same
page, while "head_page" is the next page of them.
3. Invoke "ring_buffer_lock_reserve()" with large enough "length"
so that it shot pass the end of current tail buffer page. Now the
"head_page", "commit_page" and "tail_page" points to the same page.
4. Discard current event with "ring_buffer_discard_commit()", so that
"head_page", "commit_page" and "tail_page" points to a page whose buffer
data page is now empty.
When the error scenario has been constructed, "tracing_read_pipe" will
be trapped inside a deadloop: "trace_empty()" returns 0 since
"rb_per_cpu_empty()" returns 0 when it hits the CPU containing such
constructed ring buffer. Then "trace_find_next_entry_inc()" always
return NULL since "rb_num_of_entries()" reports there's no more entry
to read. Finally "trace_seq_to_user()" returns "-EBUSY" spanking
"tracing_read_pipe" back to the start of the "waitagain" loop.
I've also written a proof-of-concept script to construct the scenario
and trigger the bug automatically, you can use it to trace and validate
my reasoning above:
https://github.com/aegistudio/RingBufferDetonator.git
Tests has been carried out on linux kernel 5.14-rc2
(2734d6c1b1a089fb593ef6a23d4b70903526fe0c), my fixed version
of kernel (for testing whether my update fixes the bug) and
some older kernels (for range of affected kernels). Test result is
also attached to the proof-of-concept repository.
Link: https://lore.kernel.org/linux-trace-devel/YPaNxsIlb2yjSi5Y@aegistudio/
Link: https://lore.kernel.org/linux-trace-devel/YPgrN85WL9VyrZ55@aegistudio
Cc: stable@vger.kernel.org
Fixes: bf41a158cacba ("ring-buffer: make reentrant")
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Haoran Luo <www@aegistudio.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1e3bac71c5053c99d438771fc9fa5082ae5d90aa upstream.
Currently the histogram logic allows the user to write "cpu" in as an
event field, and it will record the CPU that the event happened on.
The problem with this is that there's a lot of events that have "cpu"
as a real field, and using "cpu" as the CPU it ran on, makes it
impossible to run histograms on the "cpu" field of events.
For example, if I want to have a histogram on the count of the
workqueue_queue_work event on its cpu field, running:
># echo 'hist:keys=cpu' > events/workqueue/workqueue_queue_work/trigger
Gives a misleading and wrong result.
Change the command to "common_cpu" as no event should have "common_*"
fields as that's a reserved name for fields used by all events. And
this makes sense here as common_cpu would be a field used by all events.
Now we can even do:
># echo 'hist:keys=common_cpu,cpu if cpu < 100' > events/workqueue/workqueue_queue_work/trigger
># cat events/workqueue/workqueue_queue_work/hist
# event histogram
#
# trigger info: hist:keys=common_cpu,cpu:vals=hitcount:sort=hitcount:size=2048 if cpu < 100 [active]
#
{ common_cpu: 0, cpu: 2 } hitcount: 1
{ common_cpu: 0, cpu: 4 } hitcount: 1
{ common_cpu: 7, cpu: 7 } hitcount: 1
{ common_cpu: 0, cpu: 7 } hitcount: 1
{ common_cpu: 0, cpu: 1 } hitcount: 1
{ common_cpu: 0, cpu: 6 } hitcount: 2
{ common_cpu: 0, cpu: 5 } hitcount: 2
{ common_cpu: 1, cpu: 1 } hitcount: 4
{ common_cpu: 6, cpu: 6 } hitcount: 4
{ common_cpu: 5, cpu: 5 } hitcount: 14
{ common_cpu: 4, cpu: 4 } hitcount: 26
{ common_cpu: 0, cpu: 0 } hitcount: 39
{ common_cpu: 2, cpu: 2 } hitcount: 184
Now for backward compatibility, I added a trick. If "cpu" is used, and
the field is not found, it will fall back to "common_cpu" and work as
it did before. This way, it will still work for old programs that use
"cpu" to get the actual CPU, but if the event has a "cpu" as a field, it
will get that event's "cpu" field, which is probably what it wants
anyway.
I updated the tracefs/README to include documentation about both the
common_timestamp and the common_cpu. This way, if that text is present in
the README, then an application can know that common_cpu is supported over
just plain "cpu".
Link: https://lkml.kernel.org/r/20210721110053.26b4f641@oasis.local.home
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: 8b7622bf94a44 ("tracing: Add cpu field for hist triggers")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 704adfb5a9978462cd861f170201ae2b5e3d3a80 upstream.
The histogram logic was allowing events with char * pointers to be used as
normal strings. But it was easy to crash the kernel with:
# echo 'hist:keys=filename' > events/syscalls/sys_enter_openat/trigger
And open some files, and boom!
BUG: unable to handle page fault for address: 00007f2ced0c3280
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 1173fa067 P4D 1173fa067 PUD 1171b6067 PMD 1171dd067 PTE 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 6 PID: 1810 Comm: cat Not tainted 5.13.0-rc5-test+ #61
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
RIP: 0010:strlen+0x0/0x20
Code: f6 82 80 2a 0b a9 20 74 11 0f b6 50 01 48 83 c0 01 f6 82 80 2a 0b
a9 20 75 ef c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <80> 3f 00 74
10 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 c3
RSP: 0018:ffffbdbf81567b50 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff93815cdb3800 RCX: ffff9382401a22d0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 00007f2ced0c3280
RBP: 0000000000000100 R08: ffff9382409ff074 R09: ffffbdbf81567c98
R10: ffff9382409ff074 R11: 0000000000000000 R12: ffff9382409ff074
R13: 0000000000000001 R14: ffff93815a744f00 R15: 00007f2ced0c3280
FS: 00007f2ced0f8580(0000) GS:ffff93825a800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2ced0c3280 CR3: 0000000107069005 CR4: 00000000001706e0
Call Trace:
event_hist_trigger+0x463/0x5f0
? find_held_lock+0x32/0x90
? sched_clock_cpu+0xe/0xd0
? lock_release+0x155/0x440
? kernel_init_free_pages+0x6d/0x90
? preempt_count_sub+0x9b/0xd0
? kernel_init_free_pages+0x6d/0x90
? get_page_from_freelist+0x12c4/0x1680
? __rb_reserve_next+0xe5/0x460
? ring_buffer_lock_reserve+0x12a/0x3f0
event_triggers_call+0x52/0xe0
ftrace_syscall_enter+0x264/0x2c0
syscall_trace_enter.constprop.0+0x1ee/0x210
do_syscall_64+0x1c/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Where it triggered a fault on strlen(key) where key was the filename.
The reason is that filename is a char * to user space, and the histogram
code just blindly dereferenced it, with obvious bad results.
I originally tried to use strncpy_from_user/kernel_nofault() but found
that there's other places that its dereferenced and not worth the effort.
Just do not allow "char *" to act like strings.
Link: https://lkml.kernel.org/r/20210715000206.025df9d2@rorschach.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Tom Zanussi <zanussi@kernel.org>
Fixes: 79e577cbce4c4 ("tracing: Support string type key properly")
Fixes: 5967bd5c4239 ("tracing: Let filter_assign_type() detect FILTER_PTR_STRING")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 4030a6e6a6a4a42ff8c18414c9e0c93e24cc70b8 upstream.
Currently tgid_map is sized at PID_MAX_DEFAULT entries, which means that
on systems where pid_max is configured higher than PID_MAX_DEFAULT the
ftrace record-tgid option doesn't work so well. Any tasks with PIDs
higher than PID_MAX_DEFAULT are simply not recorded in tgid_map, and
don't show up in the saved_tgids file.
In particular since systemd v243 & above configure pid_max to its
highest possible 1<<22 value by default on 64 bit systems this renders
the record-tgids option of little use.
Increase the size of tgid_map to the configured pid_max instead,
allowing it to cover the full range of PIDs up to the maximum value of
PID_MAX_LIMIT if the system is configured that way.
On 64 bit systems with pid_max == PID_MAX_LIMIT this will increase the
size of tgid_map from 256KiB to 16MiB. Whilst this 64x increase in
memory overhead sounds significant 64 bit systems are presumably best
placed to accommodate it, and since tgid_map is only allocated when the
record-tgid option is actually used presumably the user would rather it
spends sufficient memory to actually record the tgids they expect.
The size of tgid_map could also increase for CONFIG_BASE_SMALL=y
configurations, but these seem unlikely to be systems upon which people
are both configuring a large pid_max and running ftrace with record-tgid
anyway.
Of note is that we only allocate tgid_map once, the first time that the
record-tgid option is enabled. Therefore its size is only set once, to
the value of pid_max at the time the record-tgid option is first
enabled. If a user increases pid_max after that point, the saved_tgids
file will not contain entries for any tasks with pids beyond the earlier
value of pid_max.
Link: https://lkml.kernel.org/r/20210701172407.889626-2-paulburton@google.com
Fixes: d914ba37d714 ("tracing: Add support for recording tgid of tasks")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paul Burton <paulburton@google.com>
[ Fixed comment coding style ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit b81b3e959adb107cd5b36c7dc5ba1364bbd31eb2 upstream.
The tgid_map array records a mapping from pid to tgid, where the index
of an entry within the array is the pid & the value stored at that index
is the tgid.
The saved_tgids_next() function iterates over pointers into the tgid_map
array & dereferences the pointers which results in the tgid, but then it
passes that dereferenced value to trace_find_tgid() which treats it as a
pid & does a further lookup within the tgid_map array. It seems likely
that the intent here was to skip over entries in tgid_map for which the
recorded tgid is zero, but instead we end up skipping over entries for
which the thread group leader hasn't yet had its own tgid recorded in
tgid_map.
A minimal fix would be to remove the call to trace_find_tgid, turning:
if (trace_find_tgid(*ptr))
into:
if (*ptr)
..but it seems like this logic can be much simpler if we simply let
seq_read() iterate over the whole tgid_map array & filter out empty
entries by returning SEQ_SKIP from saved_tgids_show(). Here we take that
approach, removing the incorrect logic here entirely.
Link: https://lkml.kernel.org/r/20210630003406.4013668-1-paulburton@google.com
Fixes: d914ba37d714 ("tracing: Add support for recording tgid of tasks")
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Paul Burton <paulburton@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 9913d5745bd720c4266805c8d29952a3702e4eca upstream.
All internal use cases for tracepoint_probe_register() is set to not ever
be called with the same function and data. If it is, it is considered a
bug, as that means the accounting of handling tracepoints is corrupted.
If the function and data for a tracepoint is already registered when
tracepoint_probe_register() is called, it will call WARN_ON_ONCE() and
return with EEXISTS.
The BPF system call can end up calling tracepoint_probe_register() with
the same data, which now means that this can trigger the warning because
of a user space process. As WARN_ON_ONCE() should not be called because
user space called a system call with bad data, there needs to be a way to
register a tracepoint without triggering a warning.
Enter tracepoint_probe_register_may_exist(), which can be called, but will
not cause a WARN_ON() if the probe already exists. It will still error out
with EEXIST, which will then be sent to the user space that performed the
BPF system call.
This keeps the previous testing for issues with other users of the
tracepoint code, while letting BPF call it with duplicated data and not
warn about it.
Link: https://lore.kernel.org/lkml/20210626135845.4080-1-penguin-kernel@I-love.SAKURA.ne.jp/
Link: https://syzkaller.appspot.com/bug?id=41f4318cf01762389f4d1c1c459da4f542fe5153
Cc: stable@vger.kernel.org
Fixes: c4f6699dfcb85 ("bpf: introduce BPF_RAW_TRACEPOINT")
Reported-by: syzbot <syzbot+721aa903751db87aa244@syzkaller.appspotmail.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot+721aa903751db87aa244@syzkaller.appspotmail.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 26c563731056c3ee66f91106c3078a8c36bb7a9e upstream.
With the addition of simple mathematical operations (plus and minus), the
parsing of the "sym-offset" modifier broke, as it took the '-' part of the
"sym-offset" as a minus, and tried to break it up into a mathematical
operation of "field.sym - offset", in which case it failed to parse
(unless the event had a field called "offset").
Both .sym and .sym-offset modifiers should not be entered into
mathematical calculations anyway. If ".sym-offset" is found in the
modifier, then simply make it not an operation that can be calculated on.
Link: https://lkml.kernel.org/r/20210707110821.188ae255@oasis.local.home
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 100719dcef447 ("tracing: Add simple expression support to hist triggers")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 89529d8b8f8daf92d9979382b8d2eb39966846ea upstream.
The trace_clock_global() tries to make sure the events between CPUs is
somewhat in order. A global value is used and updated by the latest read
of a clock. If one CPU is ahead by a little, and is read by another CPU, a
lock is taken, and if the timestamp of the other CPU is behind, it will
simply use the other CPUs timestamp.
The lock is also only taken with a "trylock" due to tracing, and strange
recursions can happen. The lock is not taken at all in NMI context.
In the case where the lock is not able to be taken, the non synced
timestamp is returned. But it will not be less than the saved global
timestamp.
The problem arises because when the time goes "backwards" the time
returned is the saved timestamp plus 1. If the lock is not taken, and the
plus one to the timestamp is returned, there's a small race that can cause
the time to go backwards!
CPU0 CPU1
---- ----
trace_clock_global() {
ts = clock() [ 1000 ]
trylock(clock_lock) [ success ]
global_ts = ts; [ 1000 ]
<interrupted by NMI>
trace_clock_global() {
ts = clock() [ 999 ]
if (ts < global_ts)
ts = global_ts + 1 [ 1001 ]
trylock(clock_lock) [ fail ]
return ts [ 1001]
}
unlock(clock_lock);
return ts; [ 1000 ]
}
trace_clock_global() {
ts = clock() [ 1000 ]
if (ts < global_ts) [ false 1000 == 1000 ]
trylock(clock_lock) [ success ]
global_ts = ts; [ 1000 ]
unlock(clock_lock)
return ts; [ 1000 ]
}
The above case shows to reads of trace_clock_global() on the same CPU, but
the second read returns one less than the first read. That is, time when
backwards, and this is not what is allowed by trace_clock_global().
This was triggered by heavy tracing and the ring buffer checker that tests
for the clock going backwards:
Ring buffer clock went backwards: 20613921464 -> 20613921463
------------[ cut here ]------------
WARNING: CPU: 2 PID: 0 at kernel/trace/ring_buffer.c:3412 check_buffer+0x1b9/0x1c0
Modules linked in:
[..]
[CPU: 2]TIME DOES NOT MATCH expected:20620711698 actual:20620711697 delta:6790234 before:20613921463 after:20613921463
[20613915818] PAGE TIME STAMP
[20613915818] delta:0
[20613915819] delta:1
[20613916035] delta:216
[20613916465] delta:430
[20613916575] delta:110
[20613916749] delta:174
[20613917248] delta:499
[20613917333] delta:85
[20613917775] delta:442
[20613917921] delta:146
[20613918321] delta:400
[20613918568] delta:247
[20613918768] delta:200
[20613919306] delta:538
[20613919353] delta:47
[20613919980] delta:627
[20613920296] delta:316
[20613920571] delta:275
[20613920862] delta:291
[20613921152] delta:290
[20613921464] delta:312
[20613921464] delta:0 TIME EXTEND
[20613921464] delta:0
This happened more than once, and always for an off by one result. It also
started happening after commit aafe104aa9096 was added.
Cc: stable@vger.kernel.org
Fixes: aafe104aa9096 ("tracing: Restructure trace_clock_global() to never block")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4fdd595e4f9a1ff6d93ec702eaecae451cfc6591 upstream.
A while ago, when the "trace" file was opened, tracing was stopped, and
code was added to stop recording the comms to saved_cmdlines, for mapping
of the pids to the task name.
Code has been added that only records the comm if a trace event occurred,
and there's no reason to not trace it if the trace file is opened.
Cc: stable@vger.kernel.org
Fixes: 7ffbd48d5cab2 ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 85550c83da421fb12dc1816c45012e1e638d2b38 upstream.
The saved_cmdlines is used to map pids to the task name, such that the
output of the tracing does not just show pids, but also gives a human
readable name for the task.
If the name is not mapped, the output looks like this:
<...>-1316 [005] ...2 132.044039: ...
Instead of this:
gnome-shell-1316 [005] ...2 132.044039: ...
The names are updated when tracing is running, but are skipped if tracing
is stopped. Unfortunately, this stops the recording of the names if the
top level tracer is stopped, and not if there's other tracers active.
The recording of a name only happens when a new event is written into a
ring buffer, so there is no need to test if tracing is on or not. If
tracing is off, then no event is written and no need to test if tracing is
off or not.
Remove the check, as it hides the names of tasks for events in the
instance buffers.
Cc: stable@vger.kernel.org
Fixes: 7ffbd48d5cab2 ("tracing: Cache comms only after an event occurred")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3e08a9f9760f4a70d633c328a76408e62d6f80a3 upstream.
We've suffered from severe kernel crashes due to memory corruption on
our production environment, like,
Call Trace:
[1640542.554277] general protection fault: 0000 [#1] SMP PTI
[1640542.554856] CPU: 17 PID: 26996 Comm: python Kdump: loaded Tainted:G
[1640542.556629] RIP: 0010:kmem_cache_alloc+0x90/0x190
[1640542.559074] RSP: 0018:ffffb16faa597df8 EFLAGS: 00010286
[1640542.559587] RAX: 0000000000000000 RBX: 0000000000400200 RCX:
0000000006e931bf
[1640542.560323] RDX: 0000000006e931be RSI: 0000000000400200 RDI:
ffff9a45ff004300
[1640542.560996] RBP: 0000000000400200 R08: 0000000000023420 R09:
0000000000000000
[1640542.561670] R10: 0000000000000000 R11: 0000000000000000 R12:
ffffffff9a20608d
[1640542.562366] R13: ffff9a45ff004300 R14: ffff9a45ff004300 R15:
696c662f65636976
[1640542.563128] FS: 00007f45d7c6f740(0000) GS:ffff9a45ff840000(0000)
knlGS:0000000000000000
[1640542.563937] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1640542.564557] CR2: 00007f45d71311a0 CR3: 000000189d63e004 CR4:
00000000003606e0
[1640542.565279] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[1640542.566069] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[1640542.566742] Call Trace:
[1640542.567009] anon_vma_clone+0x5d/0x170
[1640542.567417] __split_vma+0x91/0x1a0
[1640542.567777] do_munmap+0x2c6/0x320
[1640542.568128] vm_munmap+0x54/0x70
[1640542.569990] __x64_sys_munmap+0x22/0x30
[1640542.572005] do_syscall_64+0x5b/0x1b0
[1640542.573724] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[1640542.575642] RIP: 0033:0x7f45d6e61e27
James Wang has reproduced it stably on the latest 4.19 LTS.
After some debugging, we finally proved that it's due to ftrace
buffer out-of-bound access using a debug tool as follows:
[ 86.775200] BUG: Out-of-bounds write at addr 0xffff88aefe8b7000
[ 86.780806] no_context+0xdf/0x3c0
[ 86.784327] __do_page_fault+0x252/0x470
[ 86.788367] do_page_fault+0x32/0x140
[ 86.792145] page_fault+0x1e/0x30
[ 86.795576] strncpy_from_unsafe+0x66/0xb0
[ 86.799789] fetch_memory_string+0x25/0x40
[ 86.804002] fetch_deref_string+0x51/0x60
[ 86.808134] kprobe_trace_func+0x32d/0x3a0
[ 86.812347] kprobe_dispatcher+0x45/0x50
[ 86.816385] kprobe_ftrace_handler+0x90/0xf0
[ 86.820779] ftrace_ops_assist_func+0xa1/0x140
[ 86.825340] 0xffffffffc00750bf
[ 86.828603] do_sys_open+0x5/0x1f0
[ 86.832124] do_syscall_64+0x5b/0x1b0
[ 86.835900] entry_SYSCALL_64_after_hwframe+0x44/0xa9
commit b220c049d519 ("tracing: Check length before giving out
the filter buffer") adds length check to protect trace data
overflow introduced in 0fc1b09ff1ff, seems that this fix can't prevent
overflow entirely, the length check should also take the sizeof
entry->array[0] into account, since this array[0] is filled the
length of trace data and occupy addtional space and risk overflow.
Link: https://lkml.kernel.org/r/20210607125734.1770447-1-liangyan.peng@linux.alibaba.com
Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Xunlei Pang <xlpang@linux.alibaba.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: b220c049d519 ("tracing: Check length before giving out the filter buffer")
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Reviewed-by: yinbinbin <yinbinbin@alibabacloud.com>
Reviewed-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
Tested-by: James Wang <jnwang@linux.alibaba.com>
Signed-off-by: Liangyan <liangyan.peng@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6c14133d2d3f768e0a35128faac8aa6ed4815051 upstream.
It was reported that a bug on arm64 caused a bad ip address to be used for
updating into a nop in ftrace_init(), but the error path (rightfully)
returned -EINVAL and not -EFAULT, as the bug caused more than one error to
occur. But because -EINVAL was returned, the ftrace_bug() tried to report
what was at the location of the ip address, and read it directly. This
caused the machine to panic, as the ip was not pointing to a valid memory
address.
Instead, read the ip address with copy_from_kernel_nofault() to safely
access the memory, and if it faults, report that the address faulted,
otherwise report what was in that location.
Link: https://lore.kernel.org/lkml/20210607032329.28671-1-mark-pk.tsai@mediatek.com/
Cc: stable@vger.kernel.org
Fixes: 05736a427f7e1 ("ftrace: warn on failure to disable mcount callers")
Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit ff40e51043af63715ab413995ff46996ecf9583f ]
Commit 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown")
added an implementation of the locked_down LSM hook to SELinux, with the aim
to restrict which domains are allowed to perform operations that would breach
lockdown. This is indirectly also getting audit subsystem involved to report
events. The latter is problematic, as reported by Ondrej and Serhei, since it
can bring down the whole system via audit:
1) The audit events that are triggered due to calls to security_locked_down()
can OOM kill a machine, see below details [0].
2) It also seems to be causing a deadlock via avc_has_perm()/slow_avc_audit()
when trying to wake up kauditd, for example, when using trace_sched_switch()
tracepoint, see details in [1]. Triggering this was not via some hypothetical
corner case, but with existing tools like runqlat & runqslower from bcc, for
example, which make use of this tracepoint. Rough call sequence goes like:
rq_lock(rq) -> -------------------------+
trace_sched_switch() -> |
bpf_prog_xyz() -> +-> deadlock
selinux_lockdown() -> |
audit_log_end() -> |
wake_up_interruptible() -> |
try_to_wake_up() -> |
rq_lock(rq) --------------+
What's worse is that the intention of 59438b46471a to further restrict lockdown
settings for specific applications in respect to the global lockdown policy is
completely broken for BPF. The SELinux policy rule for the current lockdown check
looks something like this:
allow <who> <who> : lockdown { <reason> };
However, this doesn't match with the 'current' task where the security_locked_down()
is executed, example: httpd does a syscall. There is a tracing program attached
to the syscall which triggers a BPF program to run, which ends up doing a
bpf_probe_read_kernel{,_str}() helper call. The selinux_lockdown() hook does
the permission check against 'current', that is, httpd in this example. httpd
has literally zero relation to this tracing program, and it would be nonsensical
having to write an SELinux policy rule against httpd to let the tracing helper
pass. The policy in this case needs to be against the entity that is installing
the BPF program. For example, if bpftrace would generate a histogram of syscall
counts by user space application:
bpftrace -e 'tracepoint:raw_syscalls:sys_enter { @[comm] = count(); }'
bpftrace would then go and generate a BPF program from this internally. One way
of doing it [for the sake of the example] could be to call bpf_get_current_task()
helper and then access current->comm via one of bpf_probe_read_kernel{,_str}()
helpers. So the program itself has nothing to do with httpd or any other random
app doing a syscall here. The BPF program _explicitly initiated_ the lockdown
check. The allow/deny policy belongs in the context of bpftrace: meaning, you
want to grant bpftrace access to use these helpers, but other tracers on the
system like my_random_tracer _not_.
Therefore fix all three issues at the same time by taking a completely different
approach for the security_locked_down() hook, that is, move the check into the
program verification phase where we actually retrieve the BPF func proto. This
also reliably gets the task (current) that is trying to install the BPF tracing
program, e.g. bpftrace/bcc/perf/systemtap/etc, and it also fixes the OOM since
we're moving this out of the BPF helper's fast-path which can be called several
millions of times per second.
The check is then also in line with other security_locked_down() hooks in the
system where the enforcement is performed at open/load time, for example,
open_kcore() for /proc/kcore access or module_sig_check() for module signatures
just to pick few random ones. What's out of scope in the fix as well as in
other security_locked_down() hook locations /outside/ of BPF subsystem is that
if the lockdown policy changes on the fly there is no retrospective action.
This requires a different discussion, potentially complex infrastructure, and
it's also not clear whether this can be solved generically. Either way, it is
out of scope for a suitable stable fix which this one is targeting. Note that
the breakage is specifically on 59438b46471a where it started to rely on 'current'
as UAPI behavior, and _not_ earlier infrastructure such as 9d1f8be5cf42 ("bpf:
Restrict bpf when kernel lockdown is in confidentiality mode").
[0] https://bugzilla.redhat.com/show_bug.cgi?id=1955585, Jakub Hrozek says:
I starting seeing this with F-34. When I run a container that is traced with
BPF to record the syscalls it is doing, auditd is flooded with messages like:
type=AVC msg=audit(1619784520.593:282387): avc: denied { confidentiality }
for pid=476 comm="auditd" lockdown_reason="use of bpf to read kernel RAM"
scontext=system_u:system_r:auditd_t:s0 tcontext=system_u:system_r:auditd_t:s0
tclass=lockdown permissive=0
This seems to be leading to auditd running out of space in the backlog buffer
and eventually OOMs the machine.
[...]
auditd running at 99% CPU presumably processing all the messages, eventually I get:
Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded
Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152579 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152626 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152694 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_lost=6878426 audit_rate_limit=0 audit_backlog_limit=64
Apr 30 12:20:45 fedora kernel: oci-seccomp-bpf invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=-1000
Apr 30 12:20:45 fedora kernel: CPU: 0 PID: 13284 Comm: oci-seccomp-bpf Not tainted 5.11.12-300.fc34.x86_64 #1
Apr 30 12:20:45 fedora kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014
[...]
[1] https://lore.kernel.org/linux-audit/CANYvDQN7H5tVp47fbYcRasv4XF07eUbsDwT_eDCHXJUj43J7jQ@mail.gmail.com/,
Serhei Makarov says:
Upstream kernel 5.11.0-rc7 and later was found to deadlock during a
bpf_probe_read_compat() call within a sched_switch tracepoint. The problem
is reproducible with the reg_alloc3 testcase from SystemTap's BPF backend
testsuite on x86_64 as well as the runqlat, runqslower tools from bcc on
ppc64le. Example stack trace:
[...]
[ 730.868702] stack backtrace:
[ 730.869590] CPU: 1 PID: 701 Comm: in:imjournal Not tainted, 5.12.0-0.rc2.20210309git144c79ef3353.166.fc35.x86_64 #1
[ 730.871605] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
[ 730.873278] Call Trace:
[ 730.873770] dump_stack+0x7f/0xa1
[ 730.874433] check_noncircular+0xdf/0x100
[ 730.875232] __lock_acquire+0x1202/0x1e10
[ 730.876031] ? __lock_acquire+0xfc0/0x1e10
[ 730.876844] lock_acquire+0xc2/0x3a0
[ 730.877551] ? __wake_up_common_lock+0x52/0x90
[ 730.878434] ? lock_acquire+0xc2/0x3a0
[ 730.879186] ? lock_is_held_type+0xa7/0x120
[ 730.880044] ? skb_queue_tail+0x1b/0x50
[ 730.880800] _raw_spin_lock_irqsave+0x4d/0x90
[ 730.881656] ? __wake_up_common_lock+0x52/0x90
[ 730.882532] __wake_up_common_lock+0x52/0x90
[ 730.883375] audit_log_end+0x5b/0x100
[ 730.884104] slow_avc_audit+0x69/0x90
[ 730.884836] avc_has_perm+0x8b/0xb0
[ 730.885532] selinux_lockdown+0xa5/0xd0
[ 730.886297] security_locked_down+0x20/0x40
[ 730.887133] bpf_probe_read_compat+0x66/0xd0
[ 730.887983] bpf_prog_250599c5469ac7b5+0x10f/0x820
[ 730.888917] trace_call_bpf+0xe9/0x240
[ 730.889672] perf_trace_run_bpf_submit+0x4d/0xc0
[ 730.890579] perf_trace_sched_switch+0x142/0x180
[ 730.891485] ? __schedule+0x6d8/0xb20
[ 730.892209] __schedule+0x6d8/0xb20
[ 730.892899] schedule+0x5b/0xc0
[ 730.893522] exit_to_user_mode_prepare+0x11d/0x240
[ 730.894457] syscall_exit_to_user_mode+0x27/0x70
[ 730.895361] entry_SYSCALL_64_after_hwframe+0x44/0xae
[...]
Fixes: 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown")
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Reported-by: Jakub Hrozek <jhrozek@redhat.com>
Reported-by: Serhei Makarov <smakarov@redhat.com>
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jamorris@linux.microsoft.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Frank Eigler <fche@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/bpf/01135120-8bf7-df2e-cff0-1d73f1f841c3@iogearbox.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
commit aafe104aa9096827a429bc1358f8260ee565b7cc upstream.
It was reported that a fix to the ring buffer recursion detection would
cause a hung machine when performing suspend / resume testing. The
following backtrace was extracted from debugging that case:
Call Trace:
trace_clock_global+0x91/0xa0
__rb_reserve_next+0x237/0x460
ring_buffer_lock_reserve+0x12a/0x3f0
trace_buffer_lock_reserve+0x10/0x50
__trace_graph_return+0x1f/0x80
trace_graph_retur |
