From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752645Ab1ECNZp (ORCPT ); Tue, 3 May 2011 09:25:45 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:65460 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752579Ab1ECNZn (ORCPT ); Tue, 3 May 2011 09:25:43 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=WP45U1wjz2qee4w0NcLUo/6uz7nBVqnYYSP3cIqeI09WnzRfNQYGO5gIr0HZt9AwLK dXhFxv6/FeI1HV+o/w/jNL7rj40ruCKN1C9heID5SGIpDFUgXZXrqduB4yUOwTnVxIaX TLiiqt0n3nx0ie5v/vFhGzywRN33N8InrwRvQ= From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , Oleg Nesterov , Paul Mundt , Ingo Molnar , Peter Zijlstra , Will Deacon , Prasad Subject: [PATCH 5/5] sh, hw_breakpoints: Fix racy access to ptrace breakpoints Date: Tue, 3 May 2011 15:25:24 +0200 Message-Id: <1304429124-2376-6-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <1304429124-2376-1-git-send-email-fweisbec@gmail.com> References: <1304429124-2376-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: Paul Mundt Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon Cc: Prasad Link: http://lkml.kernel.org/r/1302284067-7860-6-git-send-email-fweisbec@gmail.com --- arch/sh/kernel/ptrace_32.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c index 2130ca6..3d7b209 100644 --- a/arch/sh/kernel/ptrace_32.c +++ b/arch/sh/kernel/ptrace_32.c @@ -117,7 +117,11 @@ void user_enable_single_step(struct task_struct *child) set_tsk_thread_flag(child, TIF_SINGLESTEP); + if (ptrace_get_breakpoints(child) < 0) + return; + set_single_step(child, pc); + ptrace_put_breakpoints(child); } void user_disable_single_step(struct task_struct *child) -- 1.7.3.2