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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-10-13 15:48:52 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-10-15 12:00:59 -0400 |
| commit | 6d9bd139455d9d40fec8c242985996468b34180c (patch) | |
| tree | fc2518ffac9b9ddb51d980565ae5030efbd391cb /kernel/trace | |
| parent | 848183553e431e6e9c2ea2f72421a7a1bbc6532e (diff) | |
| download | linux-6d9bd139455d9d40fec8c242985996468b34180c.tar.bz2 | |
tracing: Check return value of __create_val_fields() before using its result
After having a typo for writing a histogram trigger.
Wrote:
echo 'hist:key=pid:ts=common_timestamp.usec' > events/sched/sched_waking/trigger
Instead of:
echo 'hist:key=pid:ts=common_timestamp.usecs' > events/sched/sched_waking/trigger
and the following crash happened:
BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 4 PID: 1641 Comm: sh Not tainted 5.9.0-rc5-test+ #549
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
RIP: 0010:event_hist_trigger_func+0x70b/0x1ee0
Code: 24 08 89 d5 49 89 cc e9 8c 00 00 00 4c 89 f2 41 b9 00 10 00 00 4c 89 e1 44 89 ee 4c 89 ff e8 dc d3 ff ff 45 89 ea 4b 8b 14 d7 <f6> 42 08 04 74 17 41 8b 8f c0 00 00 00 8d 71 01 41 89 b7 c0 00 00
RSP: 0018:ffff959213d53db0 EFLAGS: 00010202
RAX: ffffffffffffffea RBX: 0000000000000000 RCX: 0000000000084c04
RDX: 0000000000000000 RSI: df7326aefebd174c RDI: 0000000000031080
RBP: 0000000000000002 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000046 R12: ffff959211dcf690
R13: 0000000000000001 R14: ffff95925a36e370 R15: ffff959251c89800
FS: 00007fb9ea934740(0000) GS:ffff95925ab00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 00000000c976c005 CR4: 00000000001706e0
Call Trace:
? trigger_process_regex+0x78/0x110
trigger_process_regex+0xc5/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xca/0x210
ksys_write+0x70/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fb9eaa29487
Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
This was caused by accessing the hlist_data fields after the call to
__create_val_fields() without checking if the creation succeed.
Link: https://lkml.kernel.org/r/20201013154852.3abd8702@gandalf.local.home
Fixes: 63a1e5de3006 ("tracing: Save normal string variables")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace_events_hist.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index c74a7d157306..96c3f86b81c5 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -3687,7 +3687,7 @@ static int create_var_field(struct hist_trigger_data *hist_data, ret = __create_val_field(hist_data, val_idx, file, var_name, expr_str, flags); - if (hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING) + if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING) hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++; return ret; |