From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752424AbcGNUXO (ORCPT ); Thu, 14 Jul 2016 16:23:14 -0400 Received: from mail.kernel.org ([198.145.29.136]:44866 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752110AbcGNUXK (ORCPT ); Thu, 14 Jul 2016 16:23:10 -0400 From: Andy Lutomirski To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Brian Gerst , Borislav Petkov , Andy Lutomirski Subject: [PATCH 05/11] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Date: Thu, 14 Jul 2016 13:22:53 -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 into a guard page, we'll recursively fault when trying to dump the contents of the guard page. Use probe_kernel_address so we can recover if this happens. Reviewed-by: Josh Poimboeuf Signed-off-by: Andy Lutomirski --- arch/x86/kernel/dumpstack_64.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index d558a8a49016..2552a1eadfed 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -272,6 +272,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, stack = sp; for (i = 0; i < kstack_depth_to_print; i++) { + unsigned long word; + if (stack >= irq_stack && stack <= irq_stack_end) { if (stack == irq_stack_end) { stack = (unsigned long *) (irq_stack_end[-1]); @@ -281,12 +283,18 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, if (kstack_end(stack)) break; } + + if (probe_kernel_address(stack, word)) + break; + if ((i % STACKSLOTS_PER_LINE) == 0) { if (i != 0) pr_cont("\n"); - printk("%s %016lx", log_lvl, *stack++); + printk("%s %016lx", log_lvl, word); } else - pr_cont(" %016lx", *stack++); + pr_cont(" %016lx", word); + + stack++; touch_nmi_watchdog(); } preempt_enable(); -- 2.7.4