From: "Theodore Ts'o" <tytso@mit.edu>
To: Aleksandr Nogikh <nogikh@google.com>
Cc: Dave Chinner <david@fromorbit.com>,
syzbot <syzbot+0c383e46e9b4827b01b1@syzkaller.appspotmail.com>,
djwong@kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [xfs?] WARNING in xfs_bmap_extents_to_btree
Date: Thu, 30 Mar 2023 12:39:53 -0400 [thread overview]
Message-ID: <20230330163953.GB629182@mit.edu> (raw)
In-Reply-To: <CANp29Y6XNE_wxx1Osa+RrfqOUP9PZhScGnMUDgQ-qqHzYe9KFg@mail.gmail.com>
On Thu, Mar 30, 2023 at 10:52:37AM +0200, Aleksandr Nogikh wrote:
> > Given this is a maliciously corrupted filesystem image, this sort of
> > warning is expected and there's probably nothing we can do to avoid
> > it short of a full filesystem verification pass during mount.
> > That's not a viable solution, so I think we should just ignore
> > syzbot when it generates this sort of warning....
>
> If it's not a warning about a kernel bug, then WARN_ON should probably
> be replaced by some more suitable reporting mechanism. Kernel coding
> style document explicitly says:
>
> "WARN*() must not be used for a condition that is expected to trigger
> easily, for example, by user space actions. pr_warn_once() is a
> possible alternative, if you need to notify the user of a problem."
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=1e760fa3596e8c7f08412712c168288b79670d78#n1223
>
Well, the question is wether a maliciously corrupted file system is a
condition which is "triggered easily". Note that it requries root
privileges to be able to mount a malciously corrupted file system,
and given that root can do all sorts of thigns that can crash the
system (example: kexec a maliciously created "kernel image" or
creating a high-priority real-time thread which starves kernel
threads), this is actually a much closer call.
- Ted
next prev parent reply other threads:[~2023-03-30 16:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-29 4:08 [syzbot] [xfs?] WARNING in xfs_bmap_extents_to_btree syzbot
2023-03-30 1:27 ` Dave Chinner
2023-03-30 8:52 ` Aleksandr Nogikh
2023-03-30 16:39 ` Theodore Ts'o [this message]
2023-03-30 22:43 ` Dave Chinner
2023-03-31 1:25 ` Darrick J. Wong
2023-03-31 20:46 ` Dave Chinner
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