Subject: KASAN: use-after-free Write in hci_sock_release

From: syzbot <[email-masked]>
Date: Tue, 23 Oct 2018 07:38:03 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    8c60c36d0b8c Add linux-next specific files for 20181019
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=163a6499400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8b6d7c4c81535e89
dashboard link: https://syzkaller.appspot.com/bug?extid=b364ed862aa07c74bc62
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

F2FS-fs (loop5): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop5): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop5): Can't find valid F2FS filesystem in 2th superblock
==================================================================
BUG: KASAN: use-after-free in atomic_dec  
include/asm-generic/atomic-instrumented.h:127 [inline]
BUG: KASAN: use-after-free in hci_sock_release+0x14f/0x3b0  
net/bluetooth/hci_sock.c:873
Write of size 4 at addr ffff880182f492a0 by task syz-executor0/7470

CPU: 1 PID: 7470 Comm: syz-executor0 Not tainted 4.19.0-rc8-next-20181019+  
#98
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+0x244/0x39d lib/dump_stack.c:113
  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
  kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278
  atomic_dec include/asm-generic/atomic-instrumented.h:127 [inline]
  hci_sock_release+0x14f/0x3b0 net/bluetooth/hci_sock.c:873
  __sock_release+0xd7/0x250 net/socket.c:580
  sock_close+0x19/0x20 net/socket.c:1142
  __fput+0x3bc/0xa70 fs/file_table.c:279
  ____fput+0x15/0x20 fs/file_table.c:312
  task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb9b189cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000457569
RDX: 000000000000000c RSI: 0000000020000240 RDI: 0000000000000006
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb9b189d6d4
R13: 00000000004bd6a4 R14: 00000000004cbf20 R15: 00000000ffffffff

Allocated by task 7468:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
  kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
  kmalloc include/linux/slab.h:546 [inline]
  kzalloc include/linux/slab.h:741 [inline]
  hci_alloc_dev+0x228/0x21a0 net/bluetooth/hci_core.c:3116
  __vhci_create_device+0x102/0x580 drivers/bluetooth/hci_vhci.c:114
  vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline]
  vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline]
  vhci_write+0x2de/0x470 drivers/bluetooth/hci_vhci.c:299
  call_write_iter include/linux/fs.h:1844 [inline]
  new_sync_write fs/read_write.c:474 [inline]
  __vfs_write+0x6b8/0x9f0 fs/read_write.c:487
  vfs_write+0x1fc/0x560 fs/read_write.c:549
  ksys_write+0x101/0x260 fs/read_write.c:598
  __do_sys_write fs/read_write.c:610 [inline]
  __se_sys_write fs/read_write.c:607 [inline]
  __x64_sys_write+0x73/0xb0 fs/read_write.c:607
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7467:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
  __cache_free mm/slab.c:3498 [inline]
  kfree+0xcf/0x230 mm/slab.c:3817
  bt_host_release+0x19/0x30 net/bluetooth/hci_sysfs.c:86
  device_release+0x7e/0x210 drivers/base/core.c:891
  kobject_cleanup lib/kobject.c:662 [inline]
  kobject_release lib/kobject.c:691 [inline]
  kref_put include/linux/kref.h:70 [inline]
  kobject_put.cold.9+0x287/0x2e4 lib/kobject.c:708
  put_device+0x20/0x30 drivers/base/core.c:2024
  hci_free_dev+0x19/0x20 net/bluetooth/hci_core.c:3208
  vhci_release+0x7e/0xf0 drivers/bluetooth/hci_vhci.c:355
  __fput+0x3bc/0xa70 fs/file_table.c:279
  ____fput+0x15/0x20 fs/file_table.c:312
  task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff880182f48240
  which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4192 bytes inside of
  8192-byte region [ffff880182f48240, ffff880182f4a240)
The buggy address belongs to the page:
page:ffffea00060bd200 count:1 mapcount:0 mapping:ffff8801da802080 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea000610f708 ffff8801da801b48 ffff8801da802080
raw: 0000000000000000 ffff880182f48240 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff880182f49180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff880182f49200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff880182f49280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                ^
  ffff880182f49300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff880182f49380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
audit: type=1800 audit(1540276897.489:32): pid=7430 uid=0 auid=4294967295  
ses=4294967295 subj==unconfined op=collect_data cause=failed(directio)  
comm="syz-executor5" name="file0" dev="sda1" ino=16559 res=0
syz-executor5 (7430) used greatest stack depth: 14640 bytes left

---
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