KASAN: out-of-bounds Read in lock_sock

KASAN: out-of-bounds Read in lock_sock_nested
Status: upstream: reported on 2020/12/01 10:30
Reported-by: syzbot+664818c59309176d03ee@syzkaller.appspotmail.com
First crash: 58d, last: 58d

Sample crash report:

==================================================================
BUG: KASAN: out-of-bounds in __lock_acquire+0x400f/0x5c00 kernel/locking/lockdep.c:4700
Read of size 8 at addr ffff8880687ab0a0 by task kworker/1:4/9766

CPU: 1 PID: 9766 Comm: kworker/1:4 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events l2cap_chan_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 __lock_acquire+0x400f/0x5c00 kernel/locking/lockdep.c:4700
 lock_acquire kernel/locking/lockdep.c:5435 [inline]
 lock_acquire+0x2a3/0x8c0 kernel/locking/lockdep.c:5400
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:359 [inline]
 lock_sock_nested+0x3b/0x110 net/core/sock.c:3036
 l2cap_sock_teardown_cb+0xa1/0x660 net/bluetooth/l2cap_sock.c:1520
 l2cap_chan_del+0xbc/0xa80 net/bluetooth/l2cap_core.c:618
 l2cap_chan_close+0x1bc/0xaf0 net/bluetooth/l2cap_core.c:823
 l2cap_chan_timeout+0x17e/0x2f0 net/bluetooth/l2cap_core.c:436
 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Allocated by task 21553:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
 kmalloc include/linux/slab.h:557 [inline]
 sk_prot_alloc+0x17a/0x300 net/core/sock.c:1666
 sk_alloc+0x32/0xbd0 net/core/sock.c:1720
 __netlink_create+0x63/0x340 net/netlink/af_netlink.c:630
 netlink_create+0x3a1/0x5d0 net/netlink/af_netlink.c:693
 __sock_create+0x3de/0x780 net/socket.c:1405
 sock_create net/socket.c:1456 [inline]
 __sys_socket+0xef/0x200 net/socket.c:1498
 __do_sys_socket net/socket.c:1507 [inline]
 __se_sys_socket net/socket.c:1505 [inline]
 __x64_sys_socket+0x6f/0xb0 net/socket.c:1505
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Last call_rcu():
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_record_aux_stack+0xc0/0xf0 mm/kasan/generic.c:346
 __call_rcu kernel/rcu/tree.c:2953 [inline]
 call_rcu+0xbb/0x700 kernel/rcu/tree.c:3027
 netlink_release+0xd43/0x1cf0 net/netlink/af_netlink.c:802
 __sock_release+0xcd/0x280 net/socket.c:596
 sock_close+0x18/0x20 net/socket.c:1255
 __fput+0x285/0x920 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x17e/0x1a0 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x38/0x260 kernel/entry/common.c:266
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff8880687ab000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 160 bytes inside of
 2048-byte region [ffff8880687ab000, ffff8880687ab800)
The buggy address belongs to the page:
page:00000000f09df1cc refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x687a8
head:00000000f09df1cc order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010042000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880687aaf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880687ab000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880687ab080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                               ^
 ffff8880687ab100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880687ab180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-upstream-net-kasan-gce	2020/11/28 01:10	net-next	fb3158ea	486f93ef	.config	log	report			info	davem@davemloft.net, johan.hedberg@gmail.com, kuba@kernel.org, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, marcel@holtmann.org, netdev@vger.kernel.org