Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758038AbbLBMwT (ORCPT ); Wed, 2 Dec 2015 07:52:19 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:49481 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756460AbbLBMwR (ORCPT ); Wed, 2 Dec 2015 07:52:17 -0500 From: Wang Nan To: , CC: , , , Wang Nan , Arnaldo Carvalho de Melo Subject: [PATCH 1/2] perf hists browser: Add NULL pointer check to prevent crash Date: Wed, 2 Dec 2015 12:51:32 +0000 Message-ID: <1449060693-236232-1-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 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=0001.0A020203.565EE979.03A5,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: aa6d17db521dd0cf3c6a17a1cdb9581b Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2556 Lines: 79 Before this patch we can trigger a segfault by following steps: 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 | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c index 33da341..9458da8 100644 --- a/tools/perf/ui/browsers/hists.c +++ b/tools/perf/ui/browsers/hists.c @@ -1280,8 +1280,10 @@ static void ui_browser__hists_seek(struct ui_browser *browser, * Moves not relative to the first visible entry invalidates its * row_offset: */ - h = rb_entry(browser->top, struct hist_entry, rb_node); - h->row_offset = 0; + if (browser->top) { + h = rb_entry(browser->top, struct hist_entry, rb_node); + h->row_offset = 0; + } /* * Here we have to check if nd is expanded (+), if it is we can't go @@ -1297,6 +1299,8 @@ 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/