From: Taeung Song <[email protected]>
After collecting samples for events 'syscalls:', perf-script with python
script doesn't occasionally work generating a segmentation fault.
The reason is that the print fmt is empty and a value of
event->print_fmt.args is NULL, so dereferencing the null pointer results
in a segmentation fault i.e.:
# perf record -e syscalls:*
# perf script -g python
# perf script -s perf-script.py
in trace_begin
syscalls__sys_enter_brk 3 79841.832099154 3777 test.sh syscall_nr=12,
brk=0
... (omitted) ...
Segmentation fault (core dumped)
For example, a format of sys_enter_getuid() hasn't
print fmt as below.
# cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_getuid/format
name: sys_enter_getuid
ID: 188
format:
field:unsigned short common_type; offset:0; size:2;
signed:0;
field:unsigned char common_flags; offset:2; size:1;
signed:0;
field:unsigned char common_preempt_count; offset:3; size:1;
signed:0;
field:int common_pid; offset:4; size:4;
signed:1;
field:int syscall_nr; offset:8; size:4;
signed:1;
print fmt: ""
So add exception handling to avoid this problem.
Signed-off-by: Taeung Song <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/scripting-engines/trace-event-perl.c | 3 +++
tools/perf/util/scripting-engines/trace-event-python.c | 3 +++
2 files changed, 6 insertions(+)
diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c
b/tools/perf/util/scripting-engines/trace-event-perl.c
index 544509c159ce..b3aabc0d4eb0 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -187,6 +187,9 @@ static void define_event_symbols(struct event_format *event,
const char *ev_name,
struct print_arg *args)
{
+ if (args == NULL)
+ return;
+
switch (args->type) {
case PRINT_NULL:
break;
diff --git a/tools/perf/util/scripting-engines/trace-event-python.c
b/tools/perf/util/scripting-engines/trace-event-python.c
index d72fafc1c800..309d90fa7698 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -205,6 +205,9 @@ static void define_event_symbols(struct event_format *event,
const char *ev_name,
struct print_arg *args)
{
+ if (args == NULL)
+ return;
+
switch (args->type) {
case PRINT_NULL:
break;
--
2.5.0
