From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932904AbbLGUHo (ORCPT ); Mon, 7 Dec 2015 15:07:44 -0500 Received: from casper.infradead.org ([85.118.1.10]:58859 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932777AbbLGUGx (ORCPT ); Mon, 7 Dec 2015 15:06:53 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Wang Nan , Namhyung Kim , Zefan Li , pi3orama@163.com, Arnaldo Carvalho de Melo Subject: [PATCH 3/5] perf hists browser: Add NULL pointer check to prevent crash Date: Mon, 7 Dec 2015 17:06:39 -0300 Message-Id: <1449518801-18511-4-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1449518801-18511-1-git-send-email-acme@kernel.org> References: <1449518801-18511-1-git-send-email-acme@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.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 Before this patch we can trigger a segfault by following steps: Step 0: Use 'perf record' to generate a perf.data without callchain Step 1: perf report Step 2: Use UP/DOWN to select an entry, don't press 'ENTER' Step 3: Use '/' to filter symbols, use a filter which returns empty result Step 4: Press 'ENTER' (notice here that the old selection is still there. This is another problem) Step 5: Press 'ENTER' to annotate that symbol Step 6: Press 'LEFT' to go out. Result: segfault: perf: Segmentation fault -------- backtrace -------- /home/wangnan/perf[0x53e568] /lib64/libc.so.6(+0x3545f)[0x7fba75d3245f] /home/wangnan/perf[0x537516] /home/wangnan/perf[0x533fef] /home/wangnan/perf[0x53b347] /home/wangnan/perf(perf_evlist__tui_browse_hists+0x96)[0x53d206] /home/wangnan/perf(cmd_report+0x1b9f)[0x442c7f] /home/wangnan/perf[0x47efa2] /home/wangnan/perf(main+0x5f5)[0x432fa5] /lib64/libc.so.6(__libc_start_main+0xf4)[0x7fba75d1ebd4] /home/wangnan/perf[0x4330d4] This is because in this case 'nd' could be NULL in ui_browser__hists_seek(), but that function never checks it. This patch adds checker for potential NULL pointer in that function. After this patch the above steps won't segfault. Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1449455746-41952-3-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/ui/browsers/hists.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c index fa9eb92c9e24..932e13d015b9 100644 --- a/tools/perf/ui/browsers/hists.c +++ b/tools/perf/ui/browsers/hists.c @@ -1033,6 +1033,9 @@ static void ui_browser__hists_seek(struct ui_browser *browser, * and stop when we printed enough lines to fill the screen. */ do_offset: + if (!nd) + return; + if (offset > 0) { do { h = rb_entry(nd, struct hist_entry, rb_node); -- 2.1.0