Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757017Ab0FIIjw (ORCPT ); Wed, 9 Jun 2010 04:39:52 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:44634 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756920Ab0FIIju (ORCPT ); Wed, 9 Jun 2010 04:39:50 -0400 From: "Ian Munsie" To: linux-kernel@vger.kernel.org Cc: Ian Munsie , Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Frederic Weisbecker , Tom Zanussi Subject: [PATCH] perf: prevent kill(0, SIGTERM); Date: Wed, 9 Jun 2010 18:38:00 +1000 Message-Id: <1276072680-17378-1-git-send-email-imunsie@au1.ibm.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2024 Lines: 53 From: Ian Munsie At exit, perf record will kill the process it was profiling by sending a SIGTERM to child_pid (if it had been initialised), but in certain situations child_pid may be 0 and perf would mistakenly kill more processes than intended. child_pid is set to the return of fork() to either 0 or the pid of the child. Ordinarily this would not present an issue as the child calls execvp to spawn the process to be profilled and would therefore never run it's sig_atexit and never attempt to kill pid 0. However, if a nonexistant binary had been passed in to perf record the call to execvp would fail and child_pid would be left set to 0. The child would then exit and it's atexit handler, finding that child_pid was initialised to 0, would call kill(0, SIGTERM), resulting in every process within it's process group being killed. In the case that perf was being run directly from the shell this typically would not be an issue as the shell isolates the process. However, if perf was being called from another program it could kill unexpected processes, which may even include X. This patch changes the logic of the test for whether child_pid was initialised to only considder positive pids as valid, thereby never attempting to kill pid 0. Signed-off-by: Ian Munsie --- tools/perf/builtin-record.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 5e5c640..300da82 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -193,7 +193,7 @@ static void sig_handler(int sig) static void sig_atexit(void) { - if (child_pid != -1) + if (child_pid > 0) kill(child_pid, SIGTERM); if (signr == -1) -- 1.7.1 -- 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/