Re: [syzbot] [crypto?] KMSAN: uninit-value in __crc32c_le_base (3)

[Dave Chinner]

On Thu, Dec 14, 2023 at 03:55:00PM +0100, Alexander Potapenko wrote:
> On Wed, Dec 13, 2023 at 10:58 PM 'Dave Chinner' via syzkaller-bugs
> <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote:
> >
> > On Thu, Dec 14, 2023 at 08:16:07AM +1100, Dave Chinner wrote:
> > > [cc linux-xfs@xxxxxxxxxxxxxxx because that's where all questions
> > > about XFS stuff should be directed, not to random individual
> > > developers. ]
> > >
> > > On Wed, Dec 13, 2023 at 11:49:50AM +0100, Alexander Potapenko wrote:
> > > > Hi Christoph, Dave,
> > > >
> > > > The repro provided by Xingwei indeed works.
> >
> > Can you please test the patch below?
> 
> It fixed the problem for me, feel free to add:
> 
> Tested-by: Alexander Potapenko <glider@xxxxxxxxxx>

Thanks.

> As for the time needed to detect the bug, note that kmemcheck was
> never used together with syzkaller, so it couldn't have the chance to
> find it.
>
> KMSAN found this bug in April
> (https://syzkaller.appspot.com/bug?extid=a6d6b8fffa294705dbd8),

KMSAN has been used for quite a long time with syzbot, however,
and it's supposed to find these problems, too. Yet it's only been
finding this for 6 months?

> only
> half a year after we started mounting XFS images on syzbot.

Really? Where did you get that from?  syzbot has been exercising XFS
filesystems since 2017 - the bug reports to the XFS list go back at
least that far.

-Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx