[ Upstream commit 1cc111b9cddc71ce161cd388f11f0e9048edffdb ]
KASAN report following issue. The root cause is when opening 'hist'
file of an instance and accessing 'trace_event_file' in hist_show(),
but 'trace_event_file' has been freed due to the instance being removed.
'hist_debug' file has the same problem. To fix it, call
tracing_{open,release}_file_tr() in file_operations callback to have
the ref count and avoid 'trace_event_file' being freed.
BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278
Read of size 8 at addr ffff242541e336b8 by task head/190
CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c #133
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x98/0xf8
show_stack+0x1c/0x30
dump_stack_lvl+0x44/0x58
print_report+0xf0/0x5a0
kasan_report+0x80/0xc0
__asan_report_load8_noabort+0x1c/0x28
hist_show+0x11e0/0x1278
seq_read_iter+0x344/0xd78
seq_read+0x128/0x1c0
vfs_read+0x198/0x6c8
ksys_read+0xf4/0x1e0
__arm64_sys_read+0x70/0xa8
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Allocated by task 188:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_alloc_info+0x20/0x30
__kasan_slab_alloc+0x6c/0x80
kmem_cache_alloc+0x15c/0x4a8
trace_create_new_event+0x84/0x348
__trace_add_new_event+0x18/0x88
event_trace_add_tracer+0xc4/0x1a0
trace_array_create_dir+0x6c/0x100
trace_array_create+0x2e8/0x568
instance_mkdir+0x48/0x80
tracefs_syscall_mkdir+0x90/0xe8
vfs_mkdir+0x3c4/0x610
do_mkdirat+0x144/0x200
__arm64_sys_mkdirat+0x8c/0xc0
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Freed by task 191:
kasan_save_stack+0x28/0x50
kasan_set_track+0x28/0x38
kasan_save_free_info+0x34/0x58
__kasan_slab_free+0xe4/0x158
kmem_cache_free+0x19c/0x508
event_file_put+0xa0/0x120
remove_event_file_dir+0x180/0x320
event_trace_del_tracer+0xb0/0x180
__remove_instance+0x224/0x508
instance_rmdir+0x44/0x78
tracefs_syscall_rmdir+0xbc/0x140
vfs_rmdir+0x1cc/0x4c8
do_rmdir+0x220/0x2b8
__arm64_sys_unlinkat+0xc0/0x100
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xb0/0x280
do_el0_svc+0x44/0x60
el0_svc+0x34/0x68
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x168/0x170
Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 00cf3d672a9dd409418647e9f98784c339c3ff63 ]
Allow a stacktrace from one event to be displayed by the end event of a
synthetic event. This is very useful when looking for the longest latency
of a sleep or something blocked on I/O.
# cd /sys/kernel/tracing/
# echo 's:block_lat pid_t pid; u64 delta; unsigned long[] stack;' > dynamic_events
# echo 'hist:keys=next_pid:ts=common_timestamp.usecs,st=stacktrace if prev_state == 1||prev_state == 2' > events/sched/sched_switch/trigger
# echo 'hist:keys=prev_pid:delta=common_timestamp.usecs-$ts,s=$st:onmax($delta).trace(block_lat,prev_pid,$delta,$s)' >> events/sched/sched_switch/trigger
The above creates a "block_lat" synthetic event that take the stacktrace of
when a task schedules out in either the interruptible or uninterruptible
states, and on a new per process max $delta (the time it was scheduled
out), will print the process id and the stacktrace.
# echo 1 > events/synthetic/block_lat/enable
# cat trace
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
kworker/u16:0-767 [006] d..4. 560.645045: block_lat: pid=767 delta=66 stack=STACK:
=> __schedule
=> schedule
=> pipe_read
=> vfs_read
=> ksys_read
=> do_syscall_64
=> 0x966000aa
<idle>-0 [003] d..4. 561.132117: block_lat: pid=0 delta=413787 stack=STACK:
=> __schedule
=> schedule
=> schedule_hrtimeout_range_clock
=> do_sys_poll
=> __x64_sys_poll
=> do_syscall_64
=> 0x966000aa
<...>-153 [006] d..4. 562.068407: block_lat: pid=153 delta=54 stack=STACK:
=> __schedule
=> schedule
=> io_schedule
=> rq_qos_wait
=> wbt_wait
=> __rq_qos_throttle
=> blk_mq_submit_bio
=> submit_bio_noacct_nocheck
=> ext4_bio_write_page
=> mpage_submit_page
=> mpage_process_page_bufs
=> mpage_prepare_extent_to_map
=> ext4_do_writepages
=> ext4_writepages
=> do_writepages
=> __writeback_single_inode
Link: https://lkml.kernel.org/r/20230117152236.010941267@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: 797311bce5c2 ("tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails")
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 4b8b3905165ef98386a3c06f196c85d21292d029 upstream.
Commit 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if
they have referenced variables") added a check to fail histogram creation
if save_hist_vars() failed to add histogram to hist_vars list. But the
commit failed to set ret to failed return code before jumping to
unregister histogram, fix it.
Link: https://lore.kernel.org/linux-trace-kernel/20230714203341.51396-1-mkhalfella@purestorage.com
Cc: stable@vger.kernel.org
Fixes: 6018b585e8c6 ("tracing/histograms: Add histograms to hist_vars if they have referenced variables")
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6018b585e8c6fa7d85d4b38d9ce49a5b67be7078 upstream.
Hist triggers can have referenced variables without having direct
variables fields. This can be the case if referenced variables are added
for trigger actions. In this case the newly added references will not
have field variables. Not taking such referenced variables into
consideration can result in a bug where it would be possible to remove
hist trigger with variables being refenced. This will result in a bug
that is easily reproducable like so
$ cd /sys/kernel/tracing
$ echo 'synthetic_sys_enter char[] comm; long id' >> synthetic_events
$ echo 'hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger
$ echo 'hist:keys=common_pid.execname,id.syscall:onmatch(raw_syscalls.sys_enter).synthetic_sys_enter($comm, id)' >> events/raw_syscalls/sys_enter/trigger
$ echo '!hist:keys=common_pid.execname,id.syscall:vals=hitcount:comm=common_pid.execname' >> events/raw_syscalls/sys_enter/trigger
[ 100.263533] ==================================================================
[ 100.264634] BUG: KASAN: slab-use-after-free in resolve_var_refs+0xc7/0x180
[ 100.265520] Read of size 8 at addr ffff88810375d0f0 by task bash/439
[ 100.266320]
[ 100.266533] CPU: 2 PID: 439 Comm: bash Not tainted 6.5.0-rc1 #4
[ 100.267277] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-20220807_005459-localhost 04/01/2014
[ 100.268561] Call Trace:
[ 100.268902] <TASK>
[ 100.269189] dump_stack_lvl+0x4c/0x70
[ 100.269680] print_report+0xc5/0x600
[ 100.270165] ? resolve_var_refs+0xc7/0x180
[ 100.270697] ? kasan_complete_mode_report_info+0x80/0x1f0
[ 100.271389] ? resolve_var_refs+0xc7/0x180
[ 100.271913] kasan_report+0xbd/0x100
[ 100.272380] ? resolve_var_refs+0xc7/0x180
[ 100.272920] __asan_load8+0x71/0xa0
[ 100.273377] resolve_var_refs+0xc7/0x180
[ 100.273888] event_hist_trigger+0x749/0x860
[ 100.274505] ? kasan_save_stack+0x2a/0x50
[ 100.275024] ? kasan_set_track+0x29/0x40
[ 100.275536] ? __pfx_event_hist_trigger+0x10/0x10
[ 100.276138] ? ksys_write+0xd1/0x170
[ 100.276607] ? do_syscall_64+0x3c/0x90
[ 100.277099] ? entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 100.277771] ? destroy_hist_data+0x446/0x470
[ 100.278324] ? event_hist_trigger_parse+0xa6c/0x3860
[ 100.278962] ? __pfx_event_hist_trigger_parse+0x10/0x10
[ 100.279627] ? __kasan_check_write+0x18/0x20
[ 100.280177] ? mutex_unlock+0x85/0xd0
[ 100.280660] ? __pfx_mutex_unlock+0x10/0x10
[ 100.281200] ? kfree+0x7b/0x120
[ 100.281619] ? ____kasan_slab_free+0x15d/0x1d0
[ 100.282197] ? event_trigger_write+0xac/0x100
[ 100.282764] ? __kasan_slab_free+0x16/0x20
[ 100.283293] ? __kmem_cache_free+0x153/0x2f0
[ 100.283844] ? sched_mm_cid_remote_clear+0xb1/0x250
[ 100.284550] ? __pfx_sched_mm_cid_remote_clear+0x10/0x10
[ 100.285221] ? event_trigger_write+0xbc/0x100
[ 100.285781] ? __kasan_check_read+0x15/0x20
[ 100.286321] ? __bitmap_weight+0x66/0xa0
[ 100.286833] ? _find_next_bit+0x46/0xe0
[ 100.287334] ? task_mm_cid_work+0x37f/0x450
[ 100.287872] event_triggers_call+0x84/0x150
[ 100.288408] trace_event_buffer_commit+0x339/0x430
[ 100.289073] ? ring_buffer_event_data+0x3f/0x60
[ 100.292189] trace_event_raw_event_sys_enter+0x8b/0xe0
[ 100.295434] syscall_trace_enter.constprop.0+0x18f/0x1b0
[ 100.298653] syscall_enter_from_user_mode+0x32/0x40
[ 100.301808] do_syscall_64+0x1a/0x90
[ 100.304748] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[ 100.307775] RIP: 0033:0x7f686c75c1cb
[ 100.310617] Code: 73 01 c3 48 8b 0d 65 3c 10 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 21 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 35 3c 10 00 f7 d8 64 89 01 48
[ 100.317847] RSP: 002b:00007ffc60137a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000021
[ 100.321200] RAX: ffffffffffffffda RBX: 000055f566469ea0 RCX: 00007f686c75c1cb
[ 100.324631] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 000000000000000a
[ 100.328104] RBP: 00007ffc60137ac0 R08: 00007f686c818460 R09: 000000000000000a
[ 100.331509] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009
[ 100.334992] R13: 0000000000000007 R14: 000000000000000a R15: 0000000000000007
[ 100.338381] </TASK>
We hit the bug because when second hist trigger has was created
has_hist_vars() returned false because hist trigger did not have
variables. As a result of that save_hist_vars() was not called to add
the trigger to trace_array->hist_vars. Later on when we attempted to
remove the first histogram find_any_var_ref() failed to detect it is
being used because it did not find the second trigger in hist_vars list.
With this change we wait until trigger actions are created so we can take
into consideration if hist trigger has variable references. Also, now we
check the return value of save_hist_vars() and fail trigger creation if
save_hist_vars() fails.
Link: https://lore.kernel.org/linux-trace-kernel/20230712223021.636335-1-mkhalfella@purestorage.com
Cc: stable@vger.kernel.org
Fixes: 067fe038e70f6 ("tracing: Add variable reference handling to hist triggers")
Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e30fbc618e97b38dbb49f1d44dcd0778d3f23b8c upstream.
Modifiers are used to change the behavior of keys. For instance, they
can grouped into buckets, converted to syscall names (from the syscall
identifier), show task->comm of the current pid, be an array of longs
that represent a stacktrace, and more.
It was found that nothing stopped a value from taking a modifier. As
values are simple counters. If this happened, it would call code that
was not expecting a modifier and crash the kernel. This was fixed by
having the ___create_val_field() function test if a modifier was present
and fail if one was. This fixed the crash.
Now there's a problem with variables. Variables are used to pass fields
from one event to another. Variables are allowed to have some modifiers,
as the processing may need to happen at the time of the event (like
stacktraces and comm names of the current pid). The issue is that it too
uses __create_val_field(). Now that fails on modifiers, variables can no
longer use them (this is a regression).
As not all modifiers are for variables, have them use a separate check.
Link: https://lore.kernel.org/linux-trace-kernel/20230523221108.064a5d82@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: e0213434fe3e4 ("tracing: Do not let histogram values have some modifiers")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e0213434fe3e4a0d118923dc98d31e7ff1cd9e45 ]
Histogram values can not be strings, stacktraces, graphs, symbols,
syscalls, or grouped in buckets or log. Give an error if a value is set to
do so.
Note, the histogram code was not prepared to handle these modifiers for
histograms and caused a bug.
Mark Rutland reported:
# echo 'p:copy_to_user __arch_copy_to_user n=$arg2' >> /sys/kernel/tracing/kprobe_events
# echo 'hist:keys=n:vals=hitcount.buckets=8:sort=hitcount' > /sys/kernel/tracing/events/kprobes/copy_to_user/trigger
# cat /sys/kernel/tracing/events/kprobes/copy_to_user/hist
[ 143.694628] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[ 143.695190] Mem abort info:
[ 143.695362] ESR = 0x0000000096000004
[ 143.695604] EC = 0x25: DABT (current EL), IL = 32 bits
[ 143.695889] SET = 0, FnV = 0
[ 143.696077] EA = 0, S1PTW = 0
[ 143.696302] FSC = 0x04: level 0 translation fault
[ 143.702381] Data abort info:
[ 143.702614] ISV = 0, ISS = 0x00000004
[ 143.702832] CM = 0, WnR = 0
[ 143.703087] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000448f9000
[ 143.703407] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
[ 143.704137] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[ 143.704714] Modules linked in:
[ 143.705273] CPU: 0 PID: 133 Comm: cat Not tainted 6.2.0-00003-g6fc512c10a7c #3
[ 143.706138] Hardware name: linux,dummy-virt (DT)
[ 143.706723] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 143.707120] pc : hist_field_name.part.0+0x14/0x140
[ 143.707504] lr : hist_field_name.part.0+0x104/0x140
[ 143.707774] sp : ffff800008333a30
[ 143.707952] x29: ffff800008333a30 x28: 0000000000000001 x27: 0000000000400cc0
[ 143.708429] x26: ffffd7a653b20260 x25: 0000000000000000 x24: ffff10d303ee5800
[ 143.708776] x23: ffffd7a6539b27b0 x22: ffff10d303fb8c00 x21: 0000000000000001
[ 143.709127] x20: ffff10d303ec2000 x19: 0000000000000000 x18: 0000000000000000
[ 143.709478] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 143.709824] x14: 0000000000000000 x13: 203a6f666e692072 x12: 6567676972742023
[ 143.710179] x11: 0a230a6d6172676f x10: 000000000000002c x9 : ffffd7a6521e018c
[ 143.710584] x8 : 000000000000002c x7 : 7f7f7f7f7f7f7f7f x6 : 000000000000002c
[ 143.710915] x5 : ffff10d303b0103e x4 : ffffd7a653b20261 x3 : 000000000000003d
[ 143.711239] x2 : 0000000000020001 x1 : 0000000000000001 x0 : 0000000000000000
[ 143.711746] Call trace:
[ 143.712115] hist_field_name.part.0+0x14/0x140
[ 143.712642] hist_field_name.part.0+0x104/0x140
[ 143.712925] hist_field_print+0x28/0x140
[ 143.713125] event_hist_trigger_print+0x174/0x4d0
[ 143.713348] hist_show+0xf8/0x980
[ 143.713521] seq_read_iter+0x1bc/0x4b0
[ 143.713711] seq_read+0x8c/0xc4
[ 143.713876] vfs_read+0xc8/0x2a4
[ 143.714043] ksys_read+0x70/0xfc
[ 143.714218] __arm64_sys_read+0x24/0x30
[ 143.714400] invoke_syscall+0x50/0x120
[ 143.714587] el0_svc_common.constprop.0+0x4c/0x100
[ 143.714807] do_el0_svc+0x44/0xd0
[ 143.714970] el0_svc+0x2c/0x84
[ 143.715134] el0t_64_sync_handler+0xbc/0x140
[ 143.715334] el0t_64_sync+0x190/0x194
[ 143.715742] Code: a9bd7bfd 910003fd a90153f3 aa0003f3 (f9400000)
[ 143.716510] ---[ end trace 0000000000000000 ]---
Segmentation fault
Link: https://lkml.kernel.org/r/20230302020810.559462599@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: c6afad49d127f ("tracing: Add hist trigger 'sym' and 'sym-offset' modifiers")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a2c54256dec7510477e2b4f4db187e638f7cac37 ]
Add the .graph suffix which shows the bar graph of the histogram value.
For example, the below example shows that the bar graph
of the histogram of the runtime for each tasks.
------
# cd /sys/kernel/debug/tracing/
# echo hist:keys=pid:vals=runtime.graph:sort=pid > \
events/sched/sched_stat_runtime/trigger
# sleep 10
# cat events/sched/sched_stat_runtime/hist
# event histogram
#
# trigger info: hist:keys=pid:vals=hitcount,runtime.graph:sort=pid:size=2048 [active]
#
{ pid: 14 } hitcount: 2 runtime:
{ pid: 16 } hitcount: 8 runtime:
{ pid: 26 } hitcount: 1 runtime:
{ pid: 57 } hitcount: 3 runtime:
{ pid: 61 } hitcount: 20 runtime: ###
{ pid: 66 } hitcount: 2 runtime:
{ pid: 70 } hitcount: 3 runtime:
{ pid: 72 } hitcount: 2 runtime:
{ pid: 145 } hitcount: 14 runtime: ####################
{ pid: 152 } hitcount: 5 runtime: #######
{ pid: 153 } hitcount: 2 runtime: ####
Totals:
Hits: 62
Entries: 11
Dropped: 0
-------
Link: https://lore.kernel.org/linux-trace-kernel/166610813953.56030.10944148382315789485.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Stable-dep-of: e0213434fe3e ("tracing: Do not let histogram values have some modifiers")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit abaa5258ce5e5887a9de049f50a85dc023391a1c ]
Add .percent suffix option to show the histogram values in percentage.
This feature is useful when we need yo undersntand the overall trend
for the histograms of large values.
E.g. this shows the runtime percentage for each tasks.
------
# cd /sys/kernel/debug/tracing/
# echo hist:keys=pid:vals=hitcount,runtime.percent:sort=pid > \
events/sched/sched_stat_runtime/trigger
# sleep 10
# cat events/sched/sched_stat_runtime/hist
# event histogram
#
# trigger info: hist:keys=pid:vals=hitcount,runtime.percent:sort=pid:size=2048 [active]
#
{ pid: 8 } hitcount: 7 runtime (%): 4.14
{ pid: 14 } hitcount: 5 runtime (%): 3.69
{ pid: 16 } hitcount: 11 runtime (%): 3.41
{ pid: 61 } hitcount: 41 runtime (%): 19.75
{ pid: 65 } hitcount: 4 runtime (%): 1.48
{ pid: 70 } hitcount: 6 runtime (%): 3.60
{ pid: 72 } hitcount: 2 runtime (%): 1.10
{ pid: 144 } hitcount: 10 runtime (%): 32.01
{ pid: 151 } hitcount: 8 runtime (%): 22.66
{ pid: 152 } hitcount: 2 runtime (%): 8.10
Totals:
Hits: 96
Entries: 10
Dropped: 0
-----
Link: https://lore.kernel.org/linux-trace-kernel/166610813077.56030.4238090506973562347.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Stable-dep-of: e0213434fe3e ("tracing: Do not let histogram values have some modifiers")
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 9f116f76fa8c04c81aef33ad870dbf9a158e5b70 upstream.
The function hist_field_name() cannot handle being passed a NULL field
parameter. It should never be NULL, but due to a previous bug, NULL was
passed to the function and the kernel crashed due to a NULL dereference.
Mark Rutland reported this to me on IRC.
The bug was fixed, but to prevent future bugs from crashing the kernel,
check the field and add a WARN_ON() if it is NULL.
Link: https://lkml.kernel.org/r/20230302020810.762384440@goodmis.org
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Mark Rutland <mark.rutland@arm.com>
Fixes: c6afad49d127f ("tracing: Add hist trigger 'sym' and 'sym-offset' modifiers")
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8b152e9150d07a885f95e1fd401fc81af202d9a4 upstream.
Function 'create_hist_field' is called recursively at
trace_events_hist.c:1954 and can return NULL-value that's why we have
to check it to avoid null pointer dereference.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Link: https://lkml.kernel.org/r/20230111120409.4111-1-n.petrova@fintech.ru
Cc: stable@vger.kernel.org
Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers")
Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>