From patchwork Mon Jun 20 23:43:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Lutomirski X-Patchwork-Id: 9189059 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 879606075E for ; Mon, 20 Jun 2016 23:45:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 76E5227BF8 for ; Mon, 20 Jun 2016 23:45:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6A3AB27E63; Mon, 20 Jun 2016 23:45:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 9B17A27BF8 for ; Mon, 20 Jun 2016 23:45:10 +0000 (UTC) Received: (qmail 26079 invoked by uid 550); 20 Jun 2016 23:44:18 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 26004 invoked from network); 20 Jun 2016 23:44:16 -0000 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, Borislav Petkov , Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Jann Horn , Heiko Carstens , Andy Lutomirski Date: Mon, 20 Jun 2016 16:43:41 -0700 Message-Id: X-Mailer: git-send-email 2.5.5 In-Reply-To: References: In-Reply-To: References: X-Virus-Scanned: ClamAV using ClamSMTP Subject: [kernel-hardening] [PATCH v3 11/13] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS X-Virus-Scanned: ClamAV using ClamSMTP 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. 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 603356a5597a..5e298638c790 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -276,6 +276,8 @@ 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]); @@ -285,12 +287,18 @@ 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();