KASAN: use-after-free Read in hci_get_auth_info

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d6efb3ac Merge tag 'tty-5.9-rc1' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14ad2134900000
kernel config: https://syzkaller.appspot.com/x/.config?x=61ec43e42a83feae
dashboard link: https://syzkaller.appspot.com/bug?extid=13010b6a10bbd82cc79c
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12fd9bc6900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+13010b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __mutex_waiter_is_first kernel/locking/mutex.c:200 [inline]
BUG: KASAN: use-after-free in __mutex_lock_common+0x12cd/0x2fc0 kernel/locking/mutex.c:1040
Read of size 8 at addr ffff88808e668060 by task syz-executor.4/19584

CPU: 0 PID: 19584 Comm: syz-executor.4 Not tainted 5.8.0-syzkaller #0
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+0x1f0/0x31e lib/dump_stack.c:118
print_address_description+0x66/0x5a0 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report+0x132/0x1d0 mm/kasan/report.c:530
__mutex_waiter_is_first kernel/locking/mutex.c:200 [inline]
__mutex_lock_common+0x12cd/0x2fc0 kernel/locking/mutex.c:1040
__mutex_lock kernel/locking/mutex.c:1103 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118
hci_get_auth_info+0x69/0x3a0 net/bluetooth/hci_conn.c:1689
hci_sock_bound_ioctl net/bluetooth/hci_sock.c:957 [inline]
hci_sock_ioctl+0x5ae/0x750 net/bluetooth/hci_sock.c:1060
sock_do_ioctl+0x7b/0x260 net/socket.c:1047
sock_ioctl+0x4aa/0x690 net/socket.c:1198
vfs_ioctl fs/ioctl.c:48 [inline]
ksys_ioctl fs/ioctl.c:753 [inline]
__do_sys_ioctl fs/ioctl.c:762 [inline]
__se_sys_ioctl+0xf9/0x160 fs/ioctl.c:760
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ccd9
Code: 2d b6 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 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f113a564c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000001d300 RCX: 000000000045ccd9
RDX: 0000000020000000 RSI: 00000000800448d7 RDI: 0000000000000005
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffd62ea93af R14: 00007f113a5659c0 R15: 000000000078bf0c

Allocated by task 6822:
save_stack mm/kasan/common.c:48 [inline]
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc+0x103/0x140 mm/kasan/common.c:494
kmem_cache_alloc_trace+0x234/0x300 mm/slab.c:3551
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
hci_alloc_dev+0x4c/0x1aa0 net/bluetooth/hci_core.c:3543
__vhci_create_device drivers/bluetooth/hci_vhci.c:99 [inline]
vhci_create_device+0x113/0x520 drivers/bluetooth/hci_vhci.c:148
process_one_work+0x789/0xfc0 kernel/workqueue.c:2269
worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Freed by task 9965:
save_stack mm/kasan/common.c:48 [inline]
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0x114/0x170 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x10a/0x220 mm/slab.c:3757
bt_host_release+0x18/0x20 net/bluetooth/hci_sysfs.c:86
device_release+0x70/0x1a0 drivers/base/core.c:1796
kobject_cleanup lib/kobject.c:704 [inline]
kobject_release lib/kobject.c:735 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1a0/0x2c0 lib/kobject.c:752
vhci_release+0x7b/0xc0 drivers/bluetooth/hci_vhci.c:341
__fput+0x2f0/0x750 fs/file_table.c:281
task_work_run+0x137/0x1c0 kernel/task_work.c:135
exit_task_work include/linux/task_work.h:25 [inline]
do_exit+0x5f3/0x1f20 kernel/exit.c:806
do_group_exit+0x161/0x2d0 kernel/exit.c:903
__do_sys_exit_group+0x13/0x20 kernel/exit.c:914
__ia32_sys_exit_group+0x0/0x40 kernel/exit.c:912
__x64_sys_exit_group+0x37/0x40 kernel/exit.c:912
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88808e668000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 96 bytes inside of
8192-byte region [ffff88808e668000, ffff88808e66a000)
The buggy address belongs to the page:
page:ffffea0002399a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0002399a00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea000217a208 ffffea0001e6c008 ffff8880aa4021c0
raw: 0000000000000000 ffff88808e668000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808e667f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88808e667f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88808e668000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88808e668080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808e668100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[Anant Thazhemadam]

Hi,

This bug doesn't seem to be getting triggered anymore for the appropriate kernel(s). 
However, given that neither the cause bisection, nor the fix bisection seem to have
suceeded, it makes it all the more difficult to zero down on the commit that might've
fixed this bug. Would it be okay to consider this a one-off, or invalid and close it off?

(unless someone can point out the commit that fixed this, of course). 

Thanks,

Anant 

[Dmitry Vyukov]

PLease resend this to kernel mailing lists/maintainers. Only they may
know about fixing commit.
I've seen a number of hci bugs recently fixed by somebody with
@chromium.org email. If you can find and CC that person, that may be
useful.

[Dmitry Vyukov]

On Fri, Sep 11, 2020 at 11:40 AM Anant Thazhemadam
<anant.th...@gmail.com> wrote:

> Understood. I just hit "Reply All" and hoped it'd loop in the mailing
> lists and maintainers as
> well (since of course, the initial bug report was sent out to everyone).
> I'll track this mail down in the kernel mailing lists and try to reach
> out to the concerned people
> on there.

Oh, you mean in the Google Groups web ui. Yes, this is not going to
work. Unfortunately, replying to kernel patches/bugs is painful. One
can't do this easily. I will CC you on the original email.

[Dmitry Vyukov]

On Sat, Aug 8, 2020 at 8:56 AM syzbot
<syzbot+13010b...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: d6efb3ac Merge tag 'tty-5.9-rc1' of git://git.kernel.org/p..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14ad2134900000
> kernel config: https://syzkaller.appspot.com/x/.config?x=61ec43e42a83feae
> dashboard link: https://syzkaller.appspot.com/bug?extid=13010b6a10bbd82cc79c
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12fd9bc6900000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+13010b...@syzkaller.appspotmail.com

+Anant who had some questions re this issue.

> --
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[Anant Thazhemadam]

On 11-09-2020 15:20, Dmitry Vyukov wrote:
> On Sat, Aug 8, 2020 at 8:56 AM syzbot
> <syzbot+13010b...@syzkaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit: d6efb3ac Merge tag 'tty-5.9-rc1' of git://git.kernel.org/p..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14ad2134900000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=61ec43e42a83feae
>> dashboard link: https://syzkaller.appspot.com/bug?extid=13010b6a10bbd82cc79c
>> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12fd9bc6900000
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+13010b...@syzkaller.appspotmail.com
> +Anant who had some questions re this issue.

This bug doesn't seem to be getting triggered anymore for the appropriate kernel(s).
However, given that neither the cause bisection, nor the fix bisection seem to have
suceeded, it makes it all the more difficult to zero down on the commit that might've
fixed this bug. Would it be okay to consider this a one-off, or invalid and close it off?
(unless someone can point out the commit that fixed this, of course).

Thanks for CCing me onto this, Dmitry.

Thanks,
Anant

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.