From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752117AbeEGKQq (ORCPT ); Mon, 7 May 2018 06:16:46 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:29949 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751889AbeEGKQl (ORCPT ); Mon, 7 May 2018 06:16:41 -0400 Subject: Re: KASAN: null-ptr-deref Write in simple_write_to_buffer To: syzbot , syzkaller-bugs@googlegroups.com, "Rafael J. Wysocki" , Len Brown , Pavel Machek References: <00000000000005aaf6056b7759ba@google.com> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk From: Tetsuo Handa Message-ID: <1a822b55-30bc-2bf3-427e-18c3d8e2b285@I-love.SAKURA.ne.jp> Date: Mon, 7 May 2018 19:15:42 +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: <00000000000005aaf6056b7759ba@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 166fa14420aa17f9a693621ef76bd107e1cb5ce8 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 7 May 2018 13:12:20 +0900 Subject: [PATCH] PM / hibernate: Fix oops at snapshot_write(). syzbot is reporting NULL pointer dereference at snapshot_write() [1]. This is because data->handle is zero-cleared by ioctl(SNAPSHOT_FREE). Fix this by checking data_of(data->handle) != NULL before using it. [1] https://syzkaller.appspot.com/bug?id=828a3c71bd344a6de8b6a31233d51a72099f27fd Signed-off-by: Tetsuo Handa Reported-by: syzbot Cc: Rafael J. Wysocki Cc: Len Brown Cc: Pavel Machek --- kernel/power/user.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/power/user.c b/kernel/power/user.c index 75c959d..abd2255 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -186,6 +186,11 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf, res = PAGE_SIZE - pg_offp; } + if (!data_of(data->handle)) { + res = -EINVAL; + goto unlock; + } + res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp, buf, count); if (res > 0) -- 1.8.3.1