Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755210AbbLGCgL (ORCPT ); Sun, 6 Dec 2015 21:36:11 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:35677 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754882AbbLGCgI (ORCPT ); Sun, 6 Dec 2015 21:36:08 -0500 From: Wang Nan To: , , CC: , , , Wang Nan Subject: [PATCH v3 2/3] perf hists browser: Add NULL pointer check to prevent crash Date: Mon, 7 Dec 2015 02:35:45 +0000 Message-ID: <1449455746-41952-3-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1449455746-41952-1-git-send-email-wangnan0@huawei.com> References: <1449455746-41952-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.5664F093.0084,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: e2a66249dede2fb6d78f955b269808e0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2167 Lines: 69 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 check it. This patch adds checker for potential NULL pointer in that function. After this patch the above steps won't segfault again. Signed-off-by: Wang Nan Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim --- 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 75ed14b..9b8a48d 100644 --- a/tools/perf/ui/browsers/hists.c +++ b/tools/perf/ui/browsers/hists.c @@ -1297,6 +1297,9 @@ 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); -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/