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SubjectKASAN: out-of-bounds Read in lock_sock_nested
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Hello,

syzbot found the following issue on:

HEAD commit: fb3158ea Merge branch 'add-chacha20-poly1305-cipher-to-ker..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=159594e9500000
kernel config: https://syzkaller.appspot.com/x/.config?x=df65150a33f23d8c
dashboard link: https://syzkaller.appspot.com/bug?extid=664818c59309176d03ee
compiler: gcc (GCC) 10.1.0-syz 20200507

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+664818c59309176d03ee@syzkaller.appspotmail.com

==================================================================
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
==================================================================


---
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