Re: [Linux-kernel-mentees] [PATCH] drm/bufs: Prevent kernel-infoleak in copy_one_buf()

From: Peilin Ye
Date: Tue Jul 28 2020 - 07:15:33 EST

On Tue, Jul 28, 2020 at 10:11:09AM +0200, Arnd Bergmann wrote:
> On Tue, Jul 28, 2020 at 3:45 AM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote:
> >
> > copy_one_buf() is copying uninitialized stack memory to userspace due to
> > the compiler not initializing holes in statically allocated structures.
> > Fix it by initializing `v` with memset().
> I would add 'potentially' somewhere in that description: it is architecture
> dependent whether there are holes in this structure as 'enum' types
> and 'long' are both dependent on the ABI, and even if there is a hole,
> it is undefined behavior whether the hold gets initialized.

I see. I will fix that up. Thank you for the advice!

Peilin Ye

> Other than that, the patch looks good.
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 5c7640ab6258 ("switch compat_drm_infobufs() to drm_ioctl_kernel()")
> > Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx>
> Acked-by: Arnd Bergmann <arnd@xxxxxxxx>