From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Jens Axboe <axboe@kernel.dk>,
syzbot <syzbot+c88a7030da47945a3cc3@syzkaller.appspotmail.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com, io-uring@vger.kernel.org
Subject: Re: [syzbot] WARNING in mntput_no_expire (2)
Date: Tue, 6 Apr 2021 14:23:28 +0000 [thread overview]
Message-ID: <YGxu4OWMLE+XXy7Z@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <YGxs5b0pY4esY7J7@zeniv-ca.linux.org.uk>
On Tue, Apr 06, 2021 at 02:15:01PM +0000, Al Viro wrote:
> I'm referring to the fact that your diff is with an already modified path_lookupat()
> _and_ those modifications have managed to introduce a bug your patch reverts.
> No terminate_walk() paired with that path_init() failure, i.e. path_init() is
> responsible for cleanups on its (many) failure exits...
I can't tell without seeing the variant your diff is against, but at a guess
it had a non-trivial amount of trouble with missed rcu_read_unlock() in
cases when path_init() fails after having done rcu_read_lock(). For trivial
testcase, consider passing -1 for dfd, so that it would fail with -EBADF.
Or passing 0 for dfd and "blah" for name (assuming your stdin is not a directory).
Sure, you could handle those in path_init() (or delay grabbing rcu_read_lock()
in there, spreading it in a bunch of branches), but duplicated cleanup logics
for a bunch of failure exits is asking for trouble.
next prev parent reply other threads:[~2021-04-06 14:23 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 9:09 [syzbot] WARNING in mntput_no_expire (2) syzbot
2021-04-01 12:16 ` syzbot
2021-04-01 18:32 ` Christian Brauner
2021-04-01 15:45 ` Christian Brauner
2021-04-01 16:09 ` Jens Axboe
2021-04-01 17:46 ` Christian Brauner
2021-04-01 17:59 ` Christian Brauner
2021-04-01 19:11 ` Al Viro
2021-04-04 2:34 ` Al Viro
2021-04-04 2:38 ` Al Viro
2021-04-04 11:34 ` Christian Brauner
2021-04-04 15:56 ` Al Viro
2021-04-04 16:40 ` Christian Brauner
2021-04-04 16:44 ` Al Viro
2021-04-04 17:05 ` Christian Brauner
2021-04-04 18:50 ` Al Viro
2021-04-04 20:17 ` Al Viro
2021-04-05 11:44 ` Christian Brauner
2021-04-05 16:18 ` Al Viro
2021-04-05 17:08 ` Christian Brauner
2021-04-05 18:23 ` Al Viro
2021-04-05 18:28 ` Al Viro
2021-04-05 20:07 ` Christian Brauner
2021-04-06 1:38 ` Al Viro
2021-04-06 2:24 ` Al Viro
2021-04-06 12:35 ` Christian Brauner
2021-04-06 13:13 ` Al Viro
2021-04-06 13:22 ` Christian Brauner
2021-04-06 14:15 ` Al Viro
2021-04-06 14:23 ` Al Viro [this message]
2021-04-06 15:37 ` Jens Axboe
2021-04-06 14:46 ` Christian Brauner
2021-04-04 16:52 ` Christian Brauner
2021-04-04 16:55 ` Christian Brauner
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