Commit-ID: e10e4ef63b54912feffb1dc48ff7d03d931b1647 Gitweb: http://git.kernel.org/tip/e10e4ef63b54912feffb1dc48ff7d03d931b1647 Author: Wang Nan <[email protected]> AuthorDate: Wed, 25 May 2016 13:44:49 +0000 Committer: Arnaldo Carvalho de Melo <[email protected]> CommitDate: Mon, 30 May 2016 12:41:45 -0300
perf evlist: Check 'base' pointer before checking refcnt when put a mmap evlist->mmap[i]->refcnt could be 0 if an evlist has no evsel or if 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: Jiri Olsa <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Zefan Li <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] [ Renamed 'mmap' variable, it is reserved in old distros such as Ubuntu 12.04, breaking the build ] Signed-off-by: Arnaldo Carvalho de Melo <[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 50d7b80..58ede32 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -856,9 +856,11 @@ 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 *md = &evlist->mmap[idx]; + + BUG_ON(md->base && atomic_read(&md->refcnt) == 0); - if (atomic_dec_and_test(&evlist->mmap[idx].refcnt)) + if (atomic_dec_and_test(&md->refcnt)) __perf_evlist__munmap(evlist, idx); }
