Commit f58385f6 authored Mar 26, 2018 by Kan Liang Committed by Arnaldo Carvalho de Melo Mar 27, 2018

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@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: ee023de0 ("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>

parent b4c786e5

tools/perf/util/mmap.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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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