From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752697AbcEYVga (ORCPT ); Wed, 25 May 2016 17:36:30 -0400 Received: from merlin.infradead.org ([205.233.59.134]:44254 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752389AbcEYVei (ORCPT ); Wed, 25 May 2016 17:34:38 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Wang Nan , He Kuang , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , pi3orama@163.com, Arnaldo Carvalho de Melo Subject: [PATCH 08/10] perf evlist: Check 'base' pointer before checking refcnt when put a mmap Date: Wed, 25 May 2016 18:34:19 -0300 Message-Id: <1464212061-7222-9-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1464212061-7222-1-git-send-email-acme@kernel.org> References: <1464212061-7222-1-git-send-email-acme@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wang Nan 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 Cc: He Kuang Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1464183898-174512-2-git-send-email-wangnan0@huawei.com [ Renamed 'mmap' variable, it is reserved in old distros such as Ubuntu 12.04, breaking the build ] Signed-off-by: Arnaldo Carvalho de Melo --- 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 50d7b80987c0..58ede3257c61 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); } -- 2.5.5