[PATCH] fbdev: Detect integer underflow at "struct fbcon_ops"->clear_margins.

[Tetsuo Handa]

On 2020/07/14 19:27, Tetsuo Handa wrote:
> On 2020/07/14 16:22, Bartlomiej Zolnierkiewicz wrote:
>> How does this patch relate to:
>>
>> 	https://marc.info/?l=linux-fbdev&m=159415024816722&w=2
>>
>> ?
>>
>> It seems to address the same issue, I've added George and Dan to Cc:.
> 
> George Kennedy's patch does not help for my case.
> 

OK. You can add

Reported-and-tested-by: syzbot <syzbot+e5fd3e65515b48c02a30 at syzkaller.appspotmail.com>

to my patch.

By the way, if

  /* bitfill_aligned() assumes that it's at least 8x8 */

is true, don't we need to also check that the rect to fill is at least
8x8 in bit_clear_margins() ? (Well, I feel did it mean multiple of 8x8 ?
Then, what is bitfill_unaligned() for ?)