From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753332AbaIHOZG (ORCPT ); Mon, 8 Sep 2014 10:25:06 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42115 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751891AbaIHOZE (ORCPT ); Mon, 8 Sep 2014 10:25:04 -0400 Message-ID: <540DBC36.3020107@oracle.com> Date: Mon, 08 Sep 2014 10:24:54 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: john@johnmccutchan.com, rlove@rlove.org, eparis@parisplace.org CC: linux-kernel@vger.kernel.org, Al Viro , Linus Torvalds Subject: Re: [PATCH] fsnotify: don't put user context if it was never assigned References: <1406640314-25201-1-git-send-email-sasha.levin@oracle.com> <540788A3.80101@oracle.com> In-Reply-To: <540788A3.80101@oracle.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ping? On 09/03/2014 05:31 PM, Sasha Levin wrote: > Ping? This is a NULL ptr deref that userspace can trigger. > > On 07/29/2014 09:25 AM, Sasha Levin wrote: >> On some failure paths we may attempt to free user context even >> if it wasn't assigned yet. This will cause a NULL ptr deref >> and a kernel BUG. >> >> Signed-off-by: Sasha Levin >> --- >> fs/notify/inotify/inotify_fsnotify.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c >> index 43ab1e1..9c8187e 100644 >> --- a/fs/notify/inotify/inotify_fsnotify.c >> +++ b/fs/notify/inotify/inotify_fsnotify.c >> @@ -165,8 +165,10 @@ static void inotify_free_group_priv(struct fsnotify_group *group) >> /* ideally the idr is empty and we won't hit the BUG in the callback */ >> idr_for_each(&group->inotify_data.idr, idr_callback, group); >> idr_destroy(&group->inotify_data.idr); >> - atomic_dec(&group->inotify_data.user->inotify_devs); >> - free_uid(group->inotify_data.user); >> + if (group->inotify_data.user) { >> + atomic_dec(&group->inotify_data.user->inotify_devs); >> + free_uid(group->inotify_data.user); >> + } >> } >> >> static void inotify_free_event(struct fsnotify_event *fsn_event) >> >