Re: KASAN: use-after-free in con_scroll​

[Greg KH <gregkh () linuxfoundation org>]

On Wed, Feb 03, 2021 at 03:04:55PM +0800, ???? wrote:
> Dear Linux kernel developers,
>
> I found a crash "KASAN: use-after-free in con_scroll+0x45c/0x620 drivers/tty/vt/vt.c:641"  when running the 
> syzkaller,  
>
> It is can be reproduced. I did not find a report about this problem. Hope it is useful.
>
>
>
>
> Linux version: Linux v5.9-rc8 (549738f15)
>
>
> The following is the crash report.
>
> ==================================================================
>
> BUG: KASAN: use-after-free in scr_memmovew include/linux/vt_buffer.h:68 [inline]
> BUG: KASAN: use-after-free in con_scroll+0x45c/0x620 drivers/tty/vt/vt.c:641
> Read of size 693770 at addr ffff8880000b894c by task syz-executor.2/7755
>
> CPU: 0 PID: 7755 Comm: syz-executor.2 Not tainted 5.1.0 #4

5.1.0 is _VERY_ old, please try reproducing this on a more modern kernel
(i.e. 5.10 or newer).

thanks,

greg k-h