From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit 9e6124d9d635957b56717f85219a88701617253f ]
Since add_probe_trace_event() can reuse tf->tevs[i] after calling clear_probe_trace_event(), this can make perf-probe crash if the 1st attempt of probe event finding fails to find an event argument, and the 2nd attempt fails to find probe point.
E.g. $ perf probe -D "task_pid_nr tsk" Failed to find 'tsk' in this function. Failed to get entry address of warn_bad_vsyscall Segmentation fault (core dumped)
Committer testing:
After the patch:
$ perf probe -D "task_pid_nr tsk" Failed to find 'tsk' in this function. Failed to get entry address of warn_bad_vsyscall Failed to get entry address of signal_fault Failed to get entry address of show_signal Failed to get entry address of umip_printk Failed to get entry address of __bad_area_nosemaphore <SNIP> Failed to get entry address of sock_set_timeout Failed to get entry address of tcp_recvmsg Probe point 'task_pid_nr' not found. Error: Failed to add events. $
Fixes: 092b1f0b5f9f ("perf probe: Clear probe_trace_event when add_probe_trace_event() fails") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Cc: Wang Nan wangnan0@huawei.com Link: http://lore.kernel.org/lkml/156856587999.25775.5145779959474477595.stgit@dev... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/probe-event.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 8394d48f8b32e..3355c445abedf 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -2329,6 +2329,7 @@ void clear_probe_trace_event(struct probe_trace_event *tev) } } zfree(&tev->args); + tev->nargs = 0; }
struct kprobe_blacklist_node {