From patchwork Mon Jun 20 23:43:40 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Lutomirski X-Patchwork-Id: 9189057 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 84EB66075E for ; Mon, 20 Jun 2016 23:45:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7158D27CDF for ; Mon, 20 Jun 2016 23:45:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 63E9E27E66; Mon, 20 Jun 2016 23:45:05 +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 A769027CDF for ; Mon, 20 Jun 2016 23:45:04 +0000 (UTC) Received: (qmail 26033 invoked by uid 550); 20 Jun 2016 23:44:17 -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 25862 invoked from network); 20 Jun 2016 23:44:14 -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 16:43:40 -0700 Message-Id: <4f079dccec047d02b6b2e1aa28650380c91ed0b7.1466466093.git.luto@kernel.org> 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 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow X-Virus-Scanned: ClamAV using ClamSMTP 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 | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index d4d085e27d04..9cdf05d768cf 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -89,7 +89,7 @@ static inline int valid_stack_ptr(struct thread_info *tinfo, else return 0; } - return p > t && p < t + THREAD_SIZE - size; + return p >= t && p < t + THREAD_SIZE - size; } unsigned long @@ -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; + while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) { unsigned long addr;