KASAN: use-after-free Read in __smsc95xx_mdio_read

[Greg KH]

On Sun, Jul 26, 2020 at 02:57:05AM -0700, syzbot wrote:
> syzbot suspects this issue was fixed by commit:
> 
> commit 7e23ab72e73bc601b4cf2983382691d9f165c8d1
> Author: Ding Xiang <dingxiang at cmss.chinamobile.com>
> Date:   Mon Mar 30 07:56:26 2020 +0000
> 
>     pinctrl: nomadik:remove unneeded variable
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13cfe3a0900000
> start commit:   7ae77150 Merge tag 'powerpc-5.8-1' of git://git.kernel.org..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d195fe572fb15312
> dashboard link: https://syzkaller.appspot.com/bug?extid=a7ebdb01bb2cc165cab6
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17046c66100000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140a8a3e100000
> 
> If the result looks correct, please mark the issue as fixed by replying with:

I think the bisection logic needs to be worked on a bit better, as how
can this patch resolve the reported problem?

thanks,

greg k-h