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authorRavi Bangoria <ravi.bangoria@linux.ibm.com>2018-04-20 20:37:58 +0530
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-04-25 10:27:55 -0400
commitba16293dad626d3e3827cfe0a1a743c1d93e76b7 (patch)
treeb2849efbc604dbdbf3e2b8906a1e511828918b74 /kernel/trace
parent1c758a2202a6b4624d0703013a2c6cfa6e7455aa (diff)
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/trace')
-rw-r--r--kernel/trace/trace_events_filter.c14
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;
}