From 9e6124d9d635957b56717f85219a88701617253f Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 16 Sep 2019 01:44:40 +0900 Subject: [PATCH] perf probe: Fix to clear tev->nargs in clear_probe_trace_event() 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 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 Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: http://lore.kernel.org/lkml/156856587999.25775.5145779959474477595.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- 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 b8e0967c5c21..91cab5f669d2 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -2331,6 +2331,7 @@ void clear_probe_trace_event(struct probe_trace_event *tev) } } zfree(&tev->args); + tev->nargs = 0; } struct kprobe_blacklist_node {