From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751938AbeCZNnT (ORCPT ); Mon, 26 Mar 2018 09:43:19 -0400 Received: from mga11.intel.com ([192.55.52.93]:60240 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbeCZNnS (ORCPT ); Mon, 26 Mar 2018 09:43:18 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,364,1517904000"; d="scan'208";a="214936743" From: kan.liang@linux.intel.com To: acme@kernel.org, mingo@redhat.com, linux-kernel@vger.kernel.org Cc: jolsa@kernel.org, namhyung@kernel.org, wangnan0@huawei.com, Kan Liang Subject: [PATCH] perf mmap: Fix accessing unmapped mmap in perf_mmap__read_done() Date: Mon, 26 Mar 2018 09:42:09 -0400 Message-Id: <1522071729-16776-1-git-send-email-kan.liang@linux.intel.com> X-Mailer: git-send-email 2.4.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kan Liang There is 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(). Fixes: ee023de05f35 ("perf mmap: Introduce perf_mmap__read_done()") Reported-by: Arnaldo Carvalho de Melo Signed-off-by: Kan Liang --- 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 38ca3ff..f6cfc52 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); } -- 2.4.11