From patchwork Thu Jul 7 18:37:44 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 646074 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 3rlmgs6PMMz9sxS; Fri, 8 Jul 2016 04:42:17 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1bLEFa-0002DJ-V3; Thu, 07 Jul 2016 18:42:14 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1bLECp-0000bB-W6 for kernel-team@lists.ubuntu.com; Thu, 07 Jul 2016 18:39:24 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1bLECo-0007rp-1U; Thu, 07 Jul 2016 18:39:22 +0000 Received: from kamal by fourier with local (Exim 4.86_2) (envelope-from ) id 1bLECl-0004wv-SN; Thu, 07 Jul 2016 11:39:19 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.19.y-ckt 45/99] MIPS: Avoid using unwind_stack() with usermode Date: Thu, 7 Jul 2016 11:37:44 -0700 Message-Id: <1467916718-18638-46-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1467916718-18638-1-git-send-email-kamal@canonical.com> References: <1467916718-18638-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Cc: linux-mips@linux-mips.org, Kamal Mostafa , James Hogan , Ralf Baechle 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 3.19.8-ckt23 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: James Hogan commit 81a76d7119f63c359750e4adeff922a31ad1135f upstream. When showing backtraces in response to traps, for example crashes and address errors (usually unaligned accesses) when they are set in debugfs to be reported, unwind_stack will be used if the PC was in the kernel text address range. However since EVA it is possible for user and kernel address ranges to overlap, and even without EVA userland can still trigger an address error by jumping to a KSeg0 address. Adjust the check to also ensure that it was running in kernel mode. I don't believe any harm can come of this problem, since unwind_stack() is sufficiently defensive, however it is only meant for unwinding kernel code, so to be correct it should use the raw backtracing instead. Signed-off-by: James Hogan Reviewed-by: Leonid Yegoshin Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11701/ Signed-off-by: Ralf Baechle (cherry picked from commit d2941a975ac745c607dfb590e92bb30bc352dad9) Signed-off-by: Kamal Mostafa --- arch/mips/kernel/traps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 7dd15e9..af1475f 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -141,7 +141,7 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs) if (!task) task = current; - if (raw_show_trace || !__kernel_text_address(pc)) { + if (raw_show_trace || user_mode(regs) || !__kernel_text_address(pc)) { show_raw_backtrace(sp); return; }