In the Linux kernel, the following vulnerability has been resolved:

llc: call sock_orphan() at release time

syzbot reported an interesting trace [1] caused by a stale sk->sk_wq
pointer in a closed llc socket.

In commit ff7b11aa481f (“net: socket: set sock->sk to NULL after
calling proto_ops::release()”) Eric Biggers hinted that some protocols
are missing a sock_orphan(), we need to perform a full audit.

In net-next, I plan to clear sock->sk from sock_orphan() and
amend Eric patch to add a warning.

[1]
BUG: KASAN: slab-use-after-free in list_empty include/linux/list.h:373 [inline]
BUG: KASAN: slab-use-after-free in waitqueue_active include/linux/wait.h:127 [inline]
BUG: KASAN: slab-use-after-free in sock_def_write_space_wfree net/core/sock.c:3384 [inline]
BUG: KASAN: slab-use-after-free in sock_wfree+0x9a8/0x9d0 net/core/sock.c:2468
Read of size 8 at addr ffff88802f4fc880 by task ksoftirqd/1/27

CPU: 1 PID: 27 Comm: ksoftirqd/1 Not tainted 6.8.0-rc1-syzkaller-00049-g6098d87eaf31 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc4/0x620 mm/kasan/report.c:488
kasan_report+0xda/0x110 mm/kasan/report.c:601
list_empty include/linux/list.h:373 [inline]
waitqueue_active include/linux/wait.h:127 [inline]
sock_def_write_space_wfree net/core/sock.c:3384 [inline]
sock_wfree+0x9a8/0x9d0 net/core/sock.c:2468
skb_release_head_state+0xa3/0x2b0 net/core/skbuff.c:1080
skb_release_all net/core/skbuff.c:1092 [inline]
napi_consume_skb+0x119/0x2b0 net/core/skbuff.c:1404
e1000_unmap_and_free_tx_resource+0x144/0x200 drivers/net/ethernet/intel/e1000/e1000_main.c:1970
e1000_clean_tx_irq drivers/net/ethernet/intel/e1000/e1000_main.c:3860 [inline]
e1000_clean+0x4a1/0x26e0 drivers/net/ethernet/intel/e1000/e1000_main.c:3801
__napi_poll.constprop.0+0xb4/0x540 net/core/dev.c:6576
napi_poll net/core/dev.c:6645 [inline]
net_rx_action+0x956/0xe90 net/core/dev.c:6778
__do_softirq+0x21a/0x8de kernel/softirq.c:553
run_ksoftirqd kernel/softirq.c:921 [inline]
run_ksoftirqd+0x31/0x60 kernel/softirq.c:913
smpboot_thread_fn+0x660/0xa10 kernel/smpboot.c:164
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>

Allocated by task 5167:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:314 [inline]
__kasan_slab_alloc+0x81/0x90 mm/kasan/common.c:340
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3813 [inline]
slab_alloc_node mm/slub.c:3860 [inline]
kmem_cache_alloc_lru+0x142/0x6f0 mm/slub.c:3879
alloc_inode_sb include/linux/fs.h:3019 [inline]
sock_alloc_inode+0x25/0x1c0 net/socket.c:308
alloc_inode+0x5d/0x220 fs/inode.c:260
new_inode_pseudo+0x16/0x80 fs/inode.c:1005
sock_alloc+0x40/0x270 net/socket.c:634
__sock_create+0xbc/0x800 net/socket.c:1535
sock_create net/socket.c:1622 [inline]
__sys_socket_create net/socket.c:1659 [inline]
__sys_socket+0x14c/0x260 net/socket.c:1706
__do_sys_socket net/socket.c:1720 [inline]
__se_sys_socket net/socket.c:1718 [inline]
__x64_sys_socket+0x72/0xb0 net/socket.c:1718
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd3/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

Freed by task 0:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3f/0x60 mm/kasan/generic.c:640
poison_slab_object mm/kasan/common.c:241 [inline]
__kasan_slab_free+0x121/0x1b0 mm/kasan/common.c:257
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2121 [inlin
—-truncated—-