Re: KASAN: use-after-free Read in h5_rx_3wire_hdr

[Dmitry Vyukov]

On Thu, Jul 25, 2019 at 11:53 AM Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
>
> Hi Dmitry,
>
> >>>> syzbot found the following crash on:
> >>>>
> >>>> HEAD commit:    6d21a41b Add linux-next specific files for 20190718
> >>>> git tree:       linux-next
> >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1377958fa00000
> >>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=3430a151e1452331
> >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=0abbda0523882250a97a
> >>>> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> >>>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=113e2bb7a00000
> >>>
> >>> +drivers/bluetooth/hci_h5.c maintainers
> >>>
> >>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >>>> Reported-by: syzbot+0abbda0523882250a97a@xxxxxxxxxxxxxxxxxxxxxxxxx
> >>>>
> >>>> ==================================================================
> >>>> BUG: KASAN: use-after-free in h5_rx_3wire_hdr+0x35d/0x3c0
> >>>> /drivers/bluetooth/hci_h5.c:438
> >>>> Read of size 1 at addr ffff8880a161d1c8 by task syz-executor.4/12040
> >>>>
> >>>> CPU: 1 PID: 12040 Comm: syz-executor.4 Not tainted 5.2.0-next-20190718 #41
> >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> >>>> Google 01/01/2011
> >>>> Call Trace:
> >>>> __dump_stack /lib/dump_stack.c:77 [inline]
> >>>> dump_stack+0x172/0x1f0 /lib/dump_stack.c:113
> >>>> print_address_description.cold+0xd4/0x306 /mm/kasan/report.c:351
> >>>> __kasan_report.cold+0x1b/0x36 /mm/kasan/report.c:482
> >>>> kasan_report+0x12/0x17 /mm/kasan/common.c:612
> >>>> __asan_report_load1_noabort+0x14/0x20 /mm/kasan/generic_report.c:129
> >>>> h5_rx_3wire_hdr+0x35d/0x3c0 /drivers/bluetooth/hci_h5.c:438
> >>>> h5_recv+0x32f/0x500 /drivers/bluetooth/hci_h5.c:563
> >>>> hci_uart_tty_receive+0x279/0x790 /drivers/bluetooth/hci_ldisc.c:600
> >>>> tiocsti /drivers/tty/tty_io.c:2197 [inline]
> >>>> tty_ioctl+0x949/0x14f0 /drivers/tty/tty_io.c:2573
> >>>> vfs_ioctl /fs/ioctl.c:46 [inline]
> >>>> file_ioctl /fs/ioctl.c:509 [inline]
> >>>> do_vfs_ioctl+0xdb6/0x13e0 /fs/ioctl.c:696
> >>>> ksys_ioctl+0xab/0xd0 /fs/ioctl.c:713
> >>>> __do_sys_ioctl /fs/ioctl.c:720 [inline]
> >>>> __se_sys_ioctl /fs/ioctl.c:718 [inline]
> >>>> __x64_sys_ioctl+0x73/0xb0 /fs/ioctl.c:718
> >>>> do_syscall_64+0xfd/0x6a0 /arch/x86/entry/common.c:296
> >>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >>>> RIP: 0033:0x459819
> >>>> Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> >>>> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
> >>>> ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> >>>> RSP: 002b:00007f7a3b459c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >>>> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459819
> >>>> RDX: 0000000020000080 RSI: 0000000000005412 RDI: 0000000000000003
> >>>> RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
> >>>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7a3b45a6d4
> >>>> R13: 00000000004c408a R14: 00000000004d7ff0 R15: 00000000ffffffff
> >>
> >> Is this happening on specific hardware?
> >
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>
> funny ;)
>
> I meant the Bluetooth chip on this machine.

I don't think there are any Bluetooth chips exposed in GCE VMs. I
would expect that this bug does not require any hardware to trigger.