From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C972C43142 for ; Mon, 25 Jun 2018 17:45:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4420D25FB4 for ; Mon, 25 Jun 2018 17:45:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="BjUo4UP5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4420D25FB4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965097AbeFYRpJ (ORCPT ); Mon, 25 Jun 2018 13:45:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:55234 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964817AbeFYRlL (ORCPT ); Mon, 25 Jun 2018 13:41:11 -0400 Received: from jouet.infradead.org (unknown [177.79.80.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A80F925C82; Mon, 25 Jun 2018 17:41:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1529948469; bh=CTxKceQzmGigHvH4SfDhL30dReZZWZRRZ7XtPcUx5dg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BjUo4UP5H5N/4rapBTR0m0lss2M5dy7EYsCLWrxF6qPDTM1ZSp7VSft7dWwFkMEX1 CSC9wouEL4sJMK8vIkwHJXerbs++hdnI62PvyC5r/aYe+4mZELZ2fst1B8UJyJrTid vBafSW3p5HI3g5aqDAwi9c2aFbAAJQVMcWYMBX3M= From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Sandipan Das , Jiri Olsa , "Naveen N . Rao" , Sukadev Bhattiprolu , Arnaldo Carvalho de Melo Subject: [PATCH 03/19] perf report powerpc: Fix crash if callchain is empty Date: Mon, 25 Jun 2018 14:40:29 -0300 Message-Id: <20180625174045.25765-4-acme@kernel.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180625174045.25765-1-acme@kernel.org> References: <20180625174045.25765-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sandipan Das For some cases, the callchain provided by the kernel may be empty. So, the callchain ip filtering code will cause a crash if we do not check whether the struct ip_callchain pointer is NULL before accessing any members. This can be observed on a powerpc64le system running Fedora 27 as shown below. # perf record -b -e cycles:u ls Before: # perf report --branch-history perf: Segmentation fault -------- backtrace -------- perf[0x1027615c] linux-vdso64.so.1(__kernel_sigtramp_rt64+0x0)[0x7fff856304d8] perf(arch_skip_callchain_idx+0x44)[0x10257c58] perf[0x1017f2e4] perf(thread__resolve_callchain+0x124)[0x1017ff5c] perf(sample__resolve_callchain+0xf0)[0x10172788] ... After: # perf report --branch-history Samples: 25 of event 'cycles:u', Event count (approx.): 2306870 Overhead Source:Line Symbol Shared Object + 11.60% _init+35736 [.] _init ls + 9.84% strcoll_l.c:137 [.] __strcoll_l libc-2.26.so + 9.16% memcpy.S:175 [.] __memcpy_power7 libc-2.26.so + 9.01% gconv_charset.h:54 [.] _nl_find_locale libc-2.26.so + 8.87% dl-addr.c:52 [.] _dl_addr libc-2.26.so + 8.83% _init+236 [.] _init ls ... Reported-by: Ravi Bangoria Signed-off-by: Sandipan Das Acked-by: Ravi Bangoria Cc: Jiri Olsa Cc: Naveen N. Rao Cc: Sukadev Bhattiprolu Link: http://lkml.kernel.org/r/20180611104049.11048-1-sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/arch/powerpc/util/skip-callchain-idx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c index 3598b8b75d27..ef5d59a5742e 100644 --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c @@ -243,7 +243,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain) u64 ip; u64 skip_slot = -1; - if (chain->nr < 3) + if (!chain || chain->nr < 3) return skip_slot; ip = chain->ips[2]; -- 2.14.3