From patchwork Wed Jan 15 21:50:42 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 311403 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 187122C0092 for ; Thu, 16 Jan 2014 09:00:25 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1W3YVZ-0002Fj-1I; Wed, 15 Jan 2014 22:00:21 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1W3YUK-0001bZ-9q for kernel-team@lists.ubuntu.com; Wed, 15 Jan 2014 21:59:04 +0000 Received: from c-67-160-231-162.hsd1.ca.comcast.net ([67.160.231.162] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1W3YOo-00073d-7W; Wed, 15 Jan 2014 21:53:22 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1W3YOl-0001Jq-Tl; Wed, 15 Jan 2014 13:53:19 -0800 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.8 028/166] ARM: 7912/1: check stack pointer in get_wchan Date: Wed, 15 Jan 2014 13:50:42 -0800 Message-Id: <1389822780-4729-29-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1389822780-4729-1-git-send-email-kamal@canonical.com> References: <1389822780-4729-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Cc: Konstantin Khlebnikov , Kamal Mostafa , Russell King X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.8.13.16 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov commit 1b15ec7a7427d4188ba91b9bbac696250a059d22 upstream. get_wchan() is lockless. Task may wakeup at any time and change its own stack, thus each next stack frame may be overwritten and filled with random stuff. /proc/$pid/stack interface had been disabled for non-current tasks, see [1] But 'wchan' still allows to trigger stack frame unwinding on volatile stack. This patch fixes oops in unwind_frame() by adding stack pointer validation on each step (as x86 code do), unwind_frame() already checks frame pointer. Also I've found another report of this oops on stackoverflow (irony). Link: http://www.spinics.net/lists/arm-kernel/msg110589.html [1] Link: http://stackoverflow.com/questions/18479894/unwind-frame-cause-a-kernel-paging-error Signed-off-by: Konstantin Khlebnikov Acked-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Kamal Mostafa --- arch/arm/kernel/process.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index c6dec5f..31c92b8 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -434,6 +434,7 @@ EXPORT_SYMBOL(dump_fpu); unsigned long get_wchan(struct task_struct *p) { struct stackframe frame; + unsigned long stack_page; int count = 0; if (!p || p == current || p->state == TASK_RUNNING) return 0; @@ -442,9 +443,11 @@ unsigned long get_wchan(struct task_struct *p) frame.sp = thread_saved_sp(p); frame.lr = 0; /* recovered from the stack */ frame.pc = thread_saved_pc(p); + stack_page = (unsigned long)task_stack_page(p); do { - int ret = unwind_frame(&frame); - if (ret < 0) + if (frame.sp < stack_page || + frame.sp >= stack_page + THREAD_SIZE || + unwind_frame(&frame) < 0) return 0; if (!in_sched_functions(frame.pc)) return frame.pc;