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From: Jens Axboe <[email protected]>
To: Al Viro <[email protected]>,
	Christian Brauner <[email protected]>
Cc: syzbot <[email protected]>,
	[email protected], [email protected],
	[email protected], [email protected]
Subject: Re: [syzbot] WARNING in mntput_no_expire (2)
Date: Tue, 6 Apr 2021 09:37:19 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 4/6/21 8:23 AM, Al Viro wrote:
> 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.

Thanks for taking care of this Al, fwiw I'm (mostly) out on vacation.

-- 
Jens Axboe


  reply	other threads:[~2021-04-06 15:37 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <[email protected]>
2021-04-01 15:45 ` [syzbot] WARNING in mntput_no_expire (2) 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
2021-04-06 15:37                                                   ` Jens Axboe [this message]
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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