From 5d8c0f0e11852d22fc3464c82453ddd1286f5d72 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 23 Mar 2023 17:19:22 -0700 Subject: [PATCH] perf lock contention: Fix msan issue in lock_contention_read() I got a report of a msan failure like below: $ sudo perf lock con -ab -- sleep 1 ... ==224416==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x5651160d6c96 in lock_contention_read util/bpf_lock_contention.c:290:8 #1 0x565115f90870 in __cmd_contention builtin-lock.c:1919:3 #2 0x565115f90870 in cmd_lock builtin-lock.c:2385:8 #3 0x565115f03a83 in run_builtin perf.c:330:11 #4 0x565115f03756 in handle_internal_command perf.c:384:8 #5 0x565115f02d53 in run_argv perf.c:428:2 #6 0x565115f02d53 in main perf.c:562:3 #7 0x7f43553bc632 in __libc_start_main #8 0x565115e865a9 in _start It was because the 'key' variable is not initialized. Actually it'd be set by bpf_map_get_next_key() but msan didn't seem to understand it. Let's make msan happy by initializing the variable. Signed-off-by: Namhyung Kim Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Ingo Molnar Cc: Jiri Olsa Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20230324001922.937634-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/bpf_lock_contention.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index 235fc71..5927bf0 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -249,7 +249,7 @@ static const char *lock_contention_get_name(struct lock_contention *con, int lock_contention_read(struct lock_contention *con) { int fd, stack, err = 0; - struct contention_key *prev_key, key; + struct contention_key *prev_key, key = {}; struct contention_data data = {}; struct lock_stat *st = NULL; struct machine *machine = con->machine; -- 2.7.4