From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933245AbcFPAaZ (ORCPT ); Wed, 15 Jun 2016 20:30:25 -0400 Received: from mail.kernel.org ([198.145.29.136]:50548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964881AbcFPA2v (ORCPT ); Wed, 15 Jun 2016 20:28:51 -0400 From: Andy Lutomirski To: "linux-kernel@vger.kernel.org" , x86@kernel.org, Borislav Petkov Cc: Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Andy Lutomirski Subject: [PATCH 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow Date: Wed, 15 Jun 2016 17:28:32 -0700 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we overflow the stack, print_context_stack will abort. Detect this case and rewind back into the valid part of the stack so that we can trace it. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/dumpstack.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index d4d085e27d04..400a2e17c1d1 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -100,6 +100,13 @@ print_context_stack(struct thread_info *tinfo, { struct stack_frame *frame = (struct stack_frame *)bp; + /* + * If we overflowed the stack into a guard page, jump back to the + * bottom of the usable stack. + */ + if ((unsigned long)tinfo - (unsigned long)stack < PAGE_SIZE) + stack = (unsigned long *)tinfo + 1; + while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) { unsigned long addr; -- 2.7.4