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| author | Ravi Bangoria <ravi.bangoria@linux.ibm.com> | 2018-04-20 17:07:58 +0200 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-04-25 16:27:55 +0200 |
| commit | ba16293dad626d3e3827cfe0a1a743c1d93e76b7 (patch) | |
| tree | b2849efbc604dbdbf3e2b8906a1e511828918b74 /kernel | |
| parent | tracing/x86: Update syscall trace events to handle new prefixed syscall func ... (diff) | |
| download | linux-ba16293dad626d3e3827cfe0a1a743c1d93e76b7.tar.xz linux-ba16293dad626d3e3827cfe0a1a743c1d93e76b7.zip | |
tracing: Fix kernel crash while using empty filter with perf
Kernel is crashing when user tries to record 'ftrace:function' event
with empty filter:
# perf record -e ftrace:function --filter="" ls
# dmesg
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
Oops: 0000 [#1] SMP PTI
...
RIP: 0010:ftrace_profile_set_filter+0x14b/0x2d0
RSP: 0018:ffffa4a7c0da7d20 EFLAGS: 00010246
RAX: ffffa4a7c0da7d64 RBX: 0000000000000000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: 0000000000000092 RDI: ffff8c48ffc968f0
...
Call Trace:
_perf_ioctl+0x54a/0x6b0
? rcu_all_qs+0x5/0x30
...
After patch:
# perf record -e ftrace:function --filter="" ls
failed to set filter "" on event ftrace:function with 22 (Invalid argument)
Also, if user tries to echo "" > filter, it used to throw an error.
This behavior got changed by commit 80765597bc58 ("tracing: Rewrite
filter logic to be simpler and faster"). This patch restores the
behavior as a side effect:
Before patch:
# echo "" > filter
#
After patch:
# echo "" > filter
bash: echo: write error: Invalid argument
#
Link: http://lkml.kernel.org/r/20180420150758.19787-1-ravi.bangoria@linux.ibm.com
Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster")
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_events_filter.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 9b4716bb8bb0..1f951b3df60c 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1499,14 +1499,14 @@ static int process_preds(struct trace_event_call *call, return ret; } - if (!nr_preds) { - prog = NULL; - } else { - prog = predicate_parse(filter_string, nr_parens, nr_preds, + if (!nr_preds) + return -EINVAL; + + prog = predicate_parse(filter_string, nr_parens, nr_preds, parse_pred, call, pe); - if (IS_ERR(prog)) - return PTR_ERR(prog); - } + if (IS_ERR(prog)) + return PTR_ERR(prog); + rcu_assign_pointer(filter->prog, prog); return 0; } |