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

[Dmitry Vyukov]

On Sat, Aug 8, 2020 at 8:56 AM syzbot
<syzbot+13010b6a10bbd82cc79c@xxxxxxxxxxxxxxxxxxxxxxxxx> 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+13010b6a10bbd82cc79c@xxxxxxxxxxxxxxxxxxxxxxxxx

+Anant who had some questions re this issue.

> ==================================================================
> 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
> ==================================================================
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/000000000000e8fb4b05ac58372e%40google.com.