From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760106AbcIPJTS (ORCPT ); Fri, 16 Sep 2016 05:19:18 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37164 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756170AbcIPJTI (ORCPT ); Fri, 16 Sep 2016 05:19:08 -0400 Date: Fri, 16 Sep 2016 02:18:12 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: jann@thejh.net, dvlasenk@redhat.com, luto@kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, jpoimboe@redhat.com, peterz@infradead.org, tglx@linutronix.de, hpa@zytor.com, bp@alien8.de, brgerst@gmail.com, linux-kernel@vger.kernel.org Reply-To: hpa@zytor.com, bp@alien8.de, tglx@linutronix.de, peterz@infradead.org, linux-kernel@vger.kernel.org, brgerst@gmail.com, jann@thejh.net, jpoimboe@redhat.com, mingo@kernel.org, torvalds@linux-foundation.org, dvlasenk@redhat.com, luto@kernel.org In-Reply-To: <337aeca8614024aa4d8d9c81053bbf8fcffbe4ad.1474003868.git.luto@kernel.org> References: <337aeca8614024aa4d8d9c81053bbf8fcffbe4ad.1474003868.git.luto@kernel.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/process: Pin the target stack in get_wchan() Git-Commit-ID: 74327a3e884a0ff895ba7b51d3488e6a177407b2 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: Commit-ID: 74327a3e884a0ff895ba7b51d3488e6a177407b2 Gitweb: http://git.kernel.org/tip/74327a3e884a0ff895ba7b51d3488e6a177407b2 Author: Andy Lutomirski AuthorDate: Thu, 15 Sep 2016 22:45:46 -0700 Committer: Ingo Molnar CommitDate: Fri, 16 Sep 2016 09:18:53 +0200 x86/process: Pin the target stack in get_wchan() This will prevent a crash if get_wchan() runs after the task stack is freed. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/337aeca8614024aa4d8d9c81053bbf8fcffbe4ad.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/process.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 0b9ed8e..4002b47 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -532,15 +532,18 @@ unsigned long thread_saved_pc(struct task_struct *tsk) */ unsigned long get_wchan(struct task_struct *p) { - unsigned long start, bottom, top, sp, fp, ip; + unsigned long start, bottom, top, sp, fp, ip, ret = 0; int count = 0; if (!p || p == current || p->state == TASK_RUNNING) return 0; + if (!try_get_task_stack(p)) + return 0; + start = (unsigned long)task_stack_page(p); if (!start) - return 0; + goto out; /* * Layout of the stack page: @@ -564,16 +567,21 @@ unsigned long get_wchan(struct task_struct *p) sp = READ_ONCE(p->thread.sp); if (sp < bottom || sp > top) - return 0; + goto out; fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp); do { if (fp < bottom || fp > top) - return 0; + goto out; ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); - if (!in_sched_functions(ip)) - return ip; + if (!in_sched_functions(ip)) { + ret = ip; + goto out; + } fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); } while (count++ < 16 && p->state != TASK_RUNNING); - return 0; + +out: + put_task_stack(p); + return ret; }