# Re: \[PATCH\] vgacon: Fix an out-of-bounds in vgacon\_scrollback\_update()

- From: Jiri Slaby \<jirislaby@kernel.org\>
- Date: 2020-07-31 04:56:19 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2020/07/6056141
- Thread: https://ratatoskr.run/dri-devel/2020/07/6033309/t.md

```text
Hi,

On 31. 07. 20, 5:23, Yang Yingliang wrote:
> void execute_one(void)
> {
> 		intptr_t res = 0;
> 	res = syz_open_dev(0xc, 4, 1);

open(/dev/tty1)

> 	if (res != -1)
> 		r[0] = res;
> *(uint16_t*)0x20000000 = 0xc;
> *(uint16_t*)0x20000002 = 0x373;
> *(uint16_t*)0x20000004 = 0x1442;
> 	syscall(__NR_ioctl, r[0], 0x5609ul, 0x20000000ul);

VT_RESIZE(12, 883)

> memcpy((void*)0x20003500, "\x7f\x45\x4c\x46\x00\x00\x00...
> 	syscall(__NR_write, r[0], 0x20003500ul, 0x381ul);

Write 381 bytes of some ELF to the tty.

OK, that's it. Thanks.

-- 
js
```