Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755808Ab1EDUaA (ORCPT ); Wed, 4 May 2011 16:30:00 -0400 Received: from hera.kernel.org ([140.211.167.34]:43420 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755506Ab1EDU37 (ORCPT ); Wed, 4 May 2011 16:29:59 -0400 Date: Wed, 4 May 2011 20:29:19 GMT From: tip-bot for Frederic Weisbecker Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, will.deacon@arm.com, a.p.zijlstra@chello.nl, lethal@linux-sh.org, fweisbec@gmail.com, stable@kernel.org, tglx@linutronix.de, oleg@redhat.com, prasad@linux.vnet.ibm.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, will.deacon@arm.com, lethal@linux-sh.org, fweisbec@gmail.com, stable@kernel.org, oleg@redhat.com, tglx@linutronix.de, mingo@elte.hu, prasad@linux.vnet.ibm.com In-Reply-To: <1302284067-7860-4-git-send-email-fweisbec@gmail.com> References: <1302284067-7860-4-git-send-email-fweisbec@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints Git-Commit-ID: 07fa7a0a8a586c01a8b416358c7012dcb9dc688d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 04 May 2011 20:29:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1889 Lines: 49 Commit-ID: 07fa7a0a8a586c01a8b416358c7012dcb9dc688d Gitweb: http://git.kernel.org/tip/07fa7a0a8a586c01a8b416358c7012dcb9dc688d Author: Frederic Weisbecker AuthorDate: Fri, 8 Apr 2011 17:29:36 +0200 Committer: Frederic Weisbecker CommitDate: Mon, 25 Apr 2011 17:33:54 +0200 powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints While the tracer accesses ptrace breakpoints, the child task may concurrently exit due to a SIGKILL and thus release its breakpoints at the same time. We can then dereference some freed pointers. To fix this, hold a reference on the child breakpoints before manipulating them. Reported-by: Oleg Nesterov Signed-off-by: Frederic Weisbecker Acked-by: Prasad Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon Cc: Paul Mundt Cc: v2.6.33.. Link: http://lkml.kernel.org/r/1302284067-7860-4-git-send-email-fweisbec@gmail.com --- arch/powerpc/kernel/ptrace.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 55613e3..4edeeb3 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long request, } case PTRACE_SET_DEBUGREG: + if (ptrace_get_breakpoints(child) < 0) + return -ESRCH; ret = ptrace_set_debugreg(child, addr, data); + ptrace_put_breakpoints(child); break; #ifdef CONFIG_PPC64 -- 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/