From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756137Ab3LQSWp (ORCPT ); Tue, 17 Dec 2013 13:22:45 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:32893 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755932Ab3LQSPj (ORCPT ); Tue, 17 Dec 2013 13:15:39 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Konstantin Khlebnikov , Russell King , Luis Henriques Subject: [PATCH 3.5 083/103] ARM: 7912/1: check stack pointer in get_wchan Date: Tue, 17 Dec 2013 18:13:12 +0000 Message-Id: <1387304012-23805-84-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1387304012-23805-1-git-send-email-luis.henriques@canonical.com> References: <1387304012-23805-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.28 -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: Luis Henriques --- 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 693b744..e5bacab 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -483,6 +483,7 @@ EXPORT_SYMBOL(kernel_thread); 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; @@ -491,9 +492,11 @@ 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; -- 1.8.3.2