From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752741Ab1ECN03 (ORCPT ); Tue, 3 May 2011 09:26:29 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:44586 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752378Ab1ECNZj (ORCPT ); Tue, 3 May 2011 09:25:39 -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=I/yOYLx6924dFhngQqf1TwQ3C6Wha0Xtbwf+Vd9WXhWNFYUukcc3bnbJV0V+gbW3Br 0LOn4zpNeMawTnVyOG6elajxXQx3+tys+DL8tavkIdxTvoDZJXHOmyWc+CqC1bZ3VGm7 4+1wnD9zq1xADNY0hboryWqKzd/dzao5sbJkQ= From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , Oleg Nesterov , Prasad , Ingo Molnar , Peter Zijlstra , Will Deacon , Paul Mundt , "v2.6.33.." Subject: [PATCH 3/5] powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints Date: Tue, 3 May 2011 15:25:22 +0200 Message-Id: <1304429124-2376-4-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: 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 -- 1.7.3.2