Re: [alsa-devel] usb/sound: slab-out-of-bounds in parse_audio_unit

[Takashi Iwai]

On Tue, 21 Nov 2017 14:51:56 +0100,
Andrey Konovalov wrote:
> 
> Hi!
> 
> I've got the following report while fuzzing the kernel with syzkaller.
> 
> On commit e1d1ea549b57790a3d8cf6300e6ef86118d692a3 (4.15-rc1).
> 
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in parse_audio_unit+0x2e08/0x31d0
> Read of size 1 at addr ffff88006998ff20 by task kworker/1:1/1495
> 
> CPU: 1 PID: 1495 Comm: kworker/1:1 Not tainted 4.14.0-57501-g9284d204d604 #119
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Workqueue: usb_hub_wq hub_event
> Call Trace:
>  __dump_stack lib/dump_stack.c:17
>  dump_stack+0xe1/0x157 lib/dump_stack.c:53
>  print_address_description+0x71/0x234 mm/kasan/report.c:252
>  kasan_report_error mm/kasan/report.c:351
>  kasan_report+0x173/0x270 mm/kasan/report.c:409
>  __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:427
>  parse_audio_feature_unit sound/usb/mixer.c:1472

Looks like that a malformed feature unit descriptor is passed while
the usb-audio driver is too naive to believe in a perfect world.
I'll provide a fix patch.


thanks,

Takashi