Re: BUG: unable to handle kernel NULL pointer dereference in mem16_serial_out

[Dmitry Vyukov]

On Thu, Dec 12, 2019 at 11:57 AM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Dec 09, 2019 at 05:38:01PM -0800, syzbot wrote:
> > syzbot has bisected this bug to:
> >
> > commit bd94c4077a0b2ecc35562c294f80f3659ecd8499
> > Author: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> > Date:   Wed Oct 28 03:46:05 2015 +0000
> >
> >     serial: support 16-bit register interface for console
>
> That would be because that is when this function was added to the kernel
> :)
>
> Again, you are asking the kernel to write to a bad place in memory, and
> then crash when that happens.  That sounds like the correct
> functionality to me...

This looks like:

#syz dup:
BUG: unable to handle kernel NULL pointer dereference in mem_serial_out

Let's continue in that thread.