Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 2/8] perf mmap: Fix accessing unmapped mmap in perf_mmap__read_done() | Date | Wed, 28 Mar 2018 15:49:13 -0300 |
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From: Kan Liang <kan.liang@linux.intel.com>
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@redhat.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Fixes: ee023de05f35 ("perf mmap: Introduce perf_mmap__read_done()") Link: http://lkml.kernel.org/r/1522071729-16776-1-git-send-email-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- 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 @@ int perf_mmap__push(struct perf_mmap *md, void *to, */ 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); } -- 2.14.3
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