From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14700C43381 for ; Tue, 26 Mar 2019 06:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D92D42075D for ; Tue, 26 Mar 2019 06:34:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553582046; bh=cfmvK8pkV+b37nbfJPZzEZ0LYqImASF0s492vzXIArs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eWWo2zQu+iYjRIr+PAJNm2R0KOTOhdeDK2OtbkW9AQHOABooB31tdDRBNnfJGRuvP EtE8ghMmIawezVydj5xwNbKCLUyPwak1sYdexl5OhmNwR8pxThX51X6+cm7B+SLnDF 0Yhylt8c0l8ptKLDJuc4wvGn82jkYloO7gqjg9K4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731800AbfCZGeF (ORCPT ); Tue, 26 Mar 2019 02:34:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:44262 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731361AbfCZGeC (ORCPT ); Tue, 26 Mar 2019 02:34:02 -0400 Received: from localhost (unknown [104.132.152.111]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4AC35206C0; Tue, 26 Mar 2019 06:34:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553582042; bh=cfmvK8pkV+b37nbfJPZzEZ0LYqImASF0s492vzXIArs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uWSpdkjW3jBtu9iuTEya7uCGqt9IHOFrSeAhJUlYAapG0CpFtDSoczE3xOVockf5T KA2T1ek6VXSsuApFRoNe/3XNac0Bv0ZeTt1l2ihbcIWKK5qIHyJR7WNNoSLYTvm7Mq P3Y3qPn+yclubbBD7sJBq1g0jrLs0oQlqYR4T0IQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , syzbot+b19c2dc2c990ea657a71@syzkaller.appspotmail.com, Alexander Potapenko , Dmitry Vyukov , Andrea Arcangeli , "Kirill A. Shutemov" , Michal Hocko , David Rientjes , Yisheng Xie , zhong jiang , Andrew Morton , Linus Torvalds Subject: [PATCH 4.14 28/41] mm, mempolicy: fix uninit memory access Date: Tue, 26 Mar 2019 15:30:05 +0900 Message-Id: <20190326042651.457089397@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190326042649.889479098@linuxfoundation.org> References: <20190326042649.889479098@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka commit 2e25644e8da4ed3a27e7b8315aaae74660be72dc upstream. Syzbot with KMSAN reports (excerpt): ================================================================== BUG: KMSAN: uninit-value in mpol_rebind_policy mm/mempolicy.c:353 [inline] BUG: KMSAN: uninit-value in mpol_rebind_mm+0x249/0x370 mm/mempolicy.c:384 CPU: 1 PID: 17420 Comm: syz-executor4 Not tainted 4.20.0-rc7+ #15 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x173/0x1d0 lib/dump_stack.c:113 kmsan_report+0x12e/0x2a0 mm/kmsan/kmsan.c:613 __msan_warning+0x82/0xf0 mm/kmsan/kmsan_instr.c:295 mpol_rebind_policy mm/mempolicy.c:353 [inline] mpol_rebind_mm+0x249/0x370 mm/mempolicy.c:384 update_tasks_nodemask+0x608/0xca0 kernel/cgroup/cpuset.c:1120 update_nodemasks_hier kernel/cgroup/cpuset.c:1185 [inline] update_nodemask kernel/cgroup/cpuset.c:1253 [inline] cpuset_write_resmask+0x2a98/0x34b0 kernel/cgroup/cpuset.c:1728 ... Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:204 [inline] kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:158 kmsan_kmalloc+0xa6/0x130 mm/kmsan/kmsan_hooks.c:176 kmem_cache_alloc+0x572/0xb90 mm/slub.c:2777 mpol_new mm/mempolicy.c:276 [inline] do_mbind mm/mempolicy.c:1180 [inline] kernel_mbind+0x8a7/0x31a0 mm/mempolicy.c:1347 __do_sys_mbind mm/mempolicy.c:1354 [inline] As it's difficult to report where exactly the uninit value resides in the mempolicy object, we have to guess a bit. mm/mempolicy.c:353 contains this part of mpol_rebind_policy(): if (!mpol_store_user_nodemask(pol) && nodes_equal(pol->w.cpuset_mems_allowed, *newmask)) "mpol_store_user_nodemask(pol)" is testing pol->flags, which I couldn't ever see being uninitialized after leaving mpol_new(). So I'll guess it's actually about accessing pol->w.cpuset_mems_allowed on line 354, but still part of statement starting on line 353. For w.cpuset_mems_allowed to be not initialized, and the nodes_equal() reachable for a mempolicy where mpol_set_nodemask() is called in do_mbind(), it seems the only possibility is a MPOL_PREFERRED policy with empty set of nodes, i.e. MPOL_LOCAL equivalent, with MPOL_F_LOCAL flag. Let's exclude such policies from the nodes_equal() check. Note the uninit access should be benign anyway, as rebinding this kind of policy is always a no-op. Therefore no actual need for stable inclusion. Link: http://lkml.kernel.org/r/a71997c3-e8ae-a787-d5ce-3db05768b27c@suse.cz Link: http://lkml.kernel.org/r/73da3e9c-cc84-509e-17d9-0c434bb9967d@suse.cz Signed-off-by: Vlastimil Babka Reported-by: syzbot+b19c2dc2c990ea657a71@syzkaller.appspotmail.com Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Andrea Arcangeli Cc: "Kirill A. Shutemov" Cc: Michal Hocko Cc: David Rientjes Cc: Yisheng Xie Cc: zhong jiang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -349,7 +349,7 @@ static void mpol_rebind_policy(struct me { if (!pol) return; - if (!mpol_store_user_nodemask(pol) && + if (!mpol_store_user_nodemask(pol) && !(pol->flags & MPOL_F_LOCAL) && nodes_equal(pol->w.cpuset_mems_allowed, *newmask)) return;