Re: BUG: unable to handle kernel paging request in snd_seq_oss_readq_puts

[Takashi Iwai]

On Wed, 01 Nov 2017 20:49:10 +0100,
Takashi Iwai wrote:
> 
> On Wed, 01 Nov 2017 19:39:46 +0100,
> Dmitry Vyukov wrote:
> > 
> > On Wed, Nov 1, 2017 at 9:38 PM, syzbot
> > <bot+31681772ec7a18dde8d3f8caf475f361a89b9514@xxxxxxxxxxxxxxxxxxxxxxxxx>
> > wrote:
> > > Hello,
> > >
> > > syzkaller hit the following crash on
> > > fc2e8b1a47c14b22c33eb087fca0db58e1f4ed0e
> > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> > > compiler: gcc (GCC) 7.1.1 20170620
> > > .config is attached
> > > Raw console output is attached.
> > > C reproducer is attached
> > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> > > for information about syzkaller reproducers
> > 
> > This also happened on more recent commits, including upstream
> > 9c323bff13f92832e03657cabdd70d731408d621 (Oct 20):
> 
> Could you try the patch below with CONFIG_SND_DEBUG=y and see whether
> it catches any bad calls?  It's already in for-next branch for 4.15.

And now I remember that it's the exactly same bug Mark Salyzyn
reported sometime ago, msgid
 <20171006171731.88889-1-salyzyn@xxxxxxxxxxx>

So this is likely hitting an invalid page, if Mark's analysis is
correct.


thanks,

Takashi