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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 7C34BC433ED for ; Fri, 7 May 2021 13:38:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 445FF61019 for ; Fri, 7 May 2021 13:38:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237287AbhEGNjv (ORCPT ); Fri, 7 May 2021 09:39:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:57792 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237286AbhEGNjv (ORCPT ); Fri, 7 May 2021 09:39:51 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 C6F7B61019; Fri, 7 May 2021 13:38:50 +0000 (UTC) Date: Fri, 7 May 2021 09:38:48 -0400 From: Steven Rostedt To: Yordan Karadzhov Cc: Linux Trace Devel Subject: [PATCH] kernel-shark: Add check for return of ksmodel_get_cpu_front() Message-ID: <20210507093848.72bf0bed@gandalf.local.home> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: Steven Rostedt (VMware) When I loaded two trace.dat files (host and guest), but the mapping of which host thread is associated to which guest vCPU was missing from the file, it caused a SEGFAULT. That's because in fillTaskGraph(), the lamGetPidCPU() calls ksmodule_get_cpu_front() which returns a negative number and does not set index. But the next line checks data[index] where index is some random number, and the application crashes. By checking the return of ksmodule_get_cpu_front(), and if it is negative do not reference data[index] and just let eFront be nullptr, the application shows no mapping, but at least it does not crash. Signed-off-by: Steven Rostedt (VMware) --- You can reproduce this with: http://rostedt.org/private/trace-no-map.tar.bz2 diff --git a/src/KsPlotTools.cpp b/src/KsPlotTools.cpp index 225dc34..abef5f8 100644 --- a/src/KsPlotTools.cpp +++ b/src/KsPlotTools.cpp @@ -1280,7 +1280,7 @@ void Graph::fillTaskGraph(int sd, int pid) false, _collectionPtr, &index); - if (index >= 0) + if (cpuFront >= 0 && index >= 0) eFront = _histoPtr->data[index]; cpuBack = ksmodel_get_cpu_back(_histoPtr, bin,