From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752609AbeDJKNe (ORCPT ); Tue, 10 Apr 2018 06:13:34 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:22587 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752057AbeDJKNd (ORCPT ); Tue, 10 Apr 2018 06:13:33 -0400 Subject: Re: KASAN: null-ptr-deref Read in xattr_getsecurity To: syzbot , "Serge E. Hallyn" , "Eric W. Biederman" References: <0000000000008d2e0d05697a693d@google.com> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk From: Tetsuo Handa Message-ID: <9d192497-8b1e-ca8d-0ed8-b3324ee1e361@I-love.SAKURA.ne.jp> Date: Tue, 10 Apr 2018 19:13:23 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <0000000000008d2e0d05697a693d@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From 904d07a6eb014f3df0c5a1ebfcfd4323276a9a76 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Tue, 10 Apr 2018 15:15:16 +0900 Subject: [PATCH] commoncap: Handle memory allocation failure. syzbot is reporting NULL pointer dereference at xattr_getsecurity() [1], for cap_inode_getsecurity() is returning sizeof(struct vfs_cap_data) when memory allocation failed. Return -ENOMEM if memory allocation failed. [1] https://syzkaller.appspot.com/bug?id=a55ba438506fe68649a5f50d2d82d56b365e0107 Signed-off-by: Tetsuo Handa Fixes: 8db6c34f1dbc8e06 ("Introduce v3 namespaced file capabilities") Reported-by: syzbot Cc: stable # 4.14+ Cc: Serge E. Hallyn Cc: Eric W. Biederman --- security/commoncap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/security/commoncap.c b/security/commoncap.c index 48620c9..1ce701f 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -449,6 +449,8 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer, magic |= VFS_CAP_FLAGS_EFFECTIVE; memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32); cap->magic_etc = cpu_to_le32(magic); + } else { + size = -ENOMEM; } } kfree(tmpbuf); -- 1.8.3.1