Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755831Ab1EDUaY (ORCPT ); Wed, 4 May 2011 16:30:24 -0400 Received: from hera.kernel.org ([140.211.167.34]:43459 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755755Ab1EDUaU (ORCPT ); Wed, 4 May 2011 16:30:20 -0400 Date: Wed, 4 May 2011 20:29:46 GMT From: tip-bot for Frederic Weisbecker Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, will.deacon@arm.com, lethal@linux-sh.org, fweisbec@gmail.com, 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, will.deacon@arm.com, a.p.zijlstra@chello.nl, lethal@linux-sh.org, fweisbec@gmail.com, oleg@redhat.com, tglx@linutronix.de, mingo@elte.hu, prasad@linux.vnet.ibm.com In-Reply-To: <1302284067-7860-5-git-send-email-fweisbec@gmail.com> References: <1302284067-7860-5-git-send-email-fweisbec@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] arm, hw_breakpoints: Fix racy access to ptrace breakpoints Git-Commit-ID: bf0b8f4b55e591ba417c2dbaff42769e1fc773b0 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 20:29:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2104 Lines: 58 Commit-ID: bf0b8f4b55e591ba417c2dbaff42769e1fc773b0 Gitweb: http://git.kernel.org/tip/bf0b8f4b55e591ba417c2dbaff42769e1fc773b0 Author: Frederic Weisbecker AuthorDate: Fri, 8 Apr 2011 17:29:36 +0200 Committer: Frederic Weisbecker CommitDate: Mon, 25 Apr 2011 17:35:18 +0200 arm, 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: Will Deacon Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Prasad Cc: Paul Mundt Link: http://lkml.kernel.org/r/1302284067-7860-5-git-send-email-fweisbec@gmail.com --- arch/arm/kernel/ptrace.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index 2bf27f3..8182f45 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -767,12 +767,20 @@ long arch_ptrace(struct task_struct *child, long request, #ifdef CONFIG_HAVE_HW_BREAKPOINT case PTRACE_GETHBPREGS: + if (ptrace_get_breakpoints(child) < 0) + return -ESRCH; + ret = ptrace_gethbpregs(child, addr, (unsigned long __user *)data); + ptrace_put_breakpoints(child); break; case PTRACE_SETHBPREGS: + if (ptrace_get_breakpoints(child) < 0) + return -ESRCH; + ret = ptrace_sethbpregs(child, addr, (unsigned long __user *)data); + ptrace_put_breakpoints(child); break; #endif -- 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/