evlist->mmap[i]->refcnt could be 0 if an evlist has no evsel or all evsels don't match the evlist during mmap. For example, when all evsels are overwritable but the evlist itself is normal. To avoid crashing, perf should check 'base' pointer before checking refcnt, and raise bug only when base is not NULL.
Signed-off-by: Wang Nan <[email protected]> Cc: He Kuang <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Zefan Li <[email protected]> Cc: [email protected] --- tools/perf/util/evlist.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index fbd0d47..f916d25 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -857,9 +857,11 @@ static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx) static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx) { - BUG_ON(atomic_read(&evlist->mmap[idx].refcnt) == 0); + struct perf_mmap *mmap = &evlist->mmap[idx]; - if (atomic_dec_and_test(&evlist->mmap[idx].refcnt)) + BUG_ON(mmap->base && atomic_read(&mmap->refcnt) == 0); + + if (atomic_dec_and_test(&mmap->refcnt)) __perf_evlist__munmap(evlist, idx); } -- 1.8.3.4
