From patchwork Thu Apr 16 20:01:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thadeu Lima de Souza Cascardo X-Patchwork-Id: 1271878 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49398s0lLRz9sP7; Fri, 17 Apr 2020 06:01:31 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1jPAhS-0005it-NP; Thu, 16 Apr 2020 20:01:26 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jPAhR-0005ie-Nu for kernel-team@lists.ubuntu.com; Thu, 16 Apr 2020 20:01:25 +0000 Received: from 1.general.cascardo.us.vpn ([10.172.70.58] helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jPAhR-0006mo-1R for kernel-team@lists.ubuntu.com; Thu, 16 Apr 2020 20:01:25 +0000 From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Subject: [X/B/D/E/F] mm: mempolicy: require at least one nodeid for MPOL_PREFERRED Date: Thu, 16 Apr 2020 17:01:12 -0300 Message-Id: <20200416200112.23079-2-cascardo@canonical.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200416200112.23079-1-cascardo@canonical.com> References: <20200416200112.23079-1-cascardo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Randy Dunlap Using an empty (malformed) nodelist that is not caught during mount option parsing leads to a stack-out-of-bounds access. The option string that was used was: "mpol=prefer:,". However, MPOL_PREFERRED requires a single node number, which is not being provided here. Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's nodeid. Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display") Reported-by: Entropy Moe <3ntr0py1337@gmail.com> Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com Cc: Lee Schermerhorn Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org Signed-off-by: Linus Torvalds (cherry picked from commit aa9f7d5172fac9bf1f09e678c35e287a40a7b7dd) CVE-2020-11565 Signed-off-by: Thadeu Lima de Souza Cascardo --- mm/mempolicy.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index fbb3258af275..787c5fc91b21 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2822,7 +2822,9 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) switch (mode) { case MPOL_PREFERRED: /* - * Insist on a nodelist of one node only + * Insist on a nodelist of one node only, although later + * we use first_node(nodes) to grab a single node, so here + * nodelist (or nodes) cannot be empty. */ if (nodelist) { char *rest = nodelist; @@ -2830,6 +2832,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) rest++; if (*rest) goto out; + if (nodes_empty(nodes)) + goto out; } break; case MPOL_INTERLEAVE: