linux-kernel - Re: [PATCH] vgacon: Fix an out-of-bounds in vgacon_scrollback

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Message-ID: <42bd14e3-ae2f-0c14-5d42-e3e7aeb11c78@kernel.org>
Date:   Fri, 31 Jul 2020 06:56:14 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Yang Yingliang <yangyingliang@...wei.com>, b.zolnierkie@...sung.com
Cc:     dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        张云海 <zhangyunhai@...ocus.com>
Subject: Re: [PATCH] vgacon: Fix an out-of-bounds in
 vgacon_scrollback_update()

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