Commit-ID: f58385f629c87a9e210108b39c1f4950d0363ad2
Gitweb: https://git.kernel.org/tip/f58385f629c87a9e210108b39c1f4950d0363ad2
Author: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
AuthorDate: Mon, 26 Mar 2018 09:42:09 -0400
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 27 Mar 2018 13:13:38 -0300
perf mmap: Fix accessing unmapped mmap in perf_mmap__read_done()
There is a segmentation fault when running 'perf trace'. For example:
[root@jouet e]# perf trace -e *chdir -o /tmp/bla perf report --ignore-vmlinux -i ../perf.data
The perf_mmap__consume() could unmap the mmap. It needs to check the
refcnt in perf_mmap__read_done().
Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Fixes: ee023de05f35 ("perf mmap: Introduce perf_mmap__read_done()")
Link: http://lkml.kernel.org/r/1522071729-16776-1-git-send-email-kan.liang@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/mmap.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index 38ca3ffb9d61..f6cfc52ff1fe 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -317,5 +317,11 @@ out:
*/
void perf_mmap__read_done(struct perf_mmap *map)
{
+ /*
+ * Check if event was unmapped due to a POLLHUP/POLLERR.
+ */
+ if (!refcount_read(&map->refcnt))
+ return;
+
map->prev = perf_mmap__read_head(map);
}
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