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

In commit ff7b11aa ("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-g6098d87e #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 [inline]
  slab_free mm/slub.c:4299 [inline]
  kmem_cache_free+0x129/0x350 mm/slub.c:4363
  i_callback+0x43/0x70 fs/inode.c:249
  rcu_do_batch kernel/rcu/tree.c:2158 [inline]
  rcu_core+0x819/0x1680 kernel/rcu/tree.c:2433
  __do_softirq+0x21a/0x8de kernel/softirq.c:553

Last potentially related work creation:
  kasan_save_stack+0x33/0x50 mm/kasan/common.c:47
  __kasan_record_aux_stack+0xba/0x100 mm/kasan/generic.c:586
  __call_rcu_common.constprop.0+0x9a/0x7b0 kernel/rcu/tree.c:2683
  destroy_inode+0x129/0x1b0 fs/inode.c:315
  iput_final fs/inode.c:1739 [inline]
  iput.part.0+0x560/0x7b0 fs/inode.c:1765
  iput+0x5c/0x80 fs/inode.c:1755
  dentry_unlink_inode+0x292/0x430 fs/dcache.c:400
  __dentry_kill+0x1ca/0x5f0 fs/dcache.c:603
  dput.part.0+0x4ac/0x9a0 fs/dcache.c:845
  dput+0x1f/0x30 fs/dcache.c:835
  __fput+0x3b9/0xb70 fs/file_table.c:384
  task_work_run+0x14d/0x240 kernel/task_work.c:180
  exit_task_work include/linux/task_work.h:38 [inline]
  do_exit+0xa8a/0x2ad0 kernel/exit.c:871
  do_group_exit+0xd4/0x2a0 kernel/exit.c:1020
  __do_sys_exit_group kernel/exit.c:1031 [inline]
  __se_sys_exit_group kernel/exit.c:1029 [inline]
  __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1029
  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

The buggy address belongs to the object at ffff88802f4fc800
 which belongs to the cache sock_inode_cache of size 1408
The buggy address is located 128 bytes inside of
 freed 1408-byte region [ffff88802f4fc800, ffff88802f4fcd80)

The buggy address belongs to the physical page:
page:ffffea0000bd3e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2f4f8
head:ffffea0000bd3e00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888013b06b40 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080150015 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_RECLAIMABLE), pid 4956, tgid 4956 (sshd), ts 31423924727, free_ts 0
  set_page_owner include/linux/page_owner.h:31 [inline]
  post_alloc_hook+0x2d0/0x350 mm/page_alloc.c:1533
  prep_new_page mm/page_alloc.c:1540 [inline]
  get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3311
  __alloc_pages+0x22f/0x2440 mm/page_alloc.c:4567
  __alloc_pages_node include/linux/gfp.h:238 [inline]
  alloc_pages_node include/linux/gfp.h:261 [inline]
  alloc_slab_page mm/slub.c:2190 [inline]
  allocate_slab mm/slub.c:2354 [inline]
  new_slab+0xcc/0x3a0 mm/slub.c:2407
  ___slab_alloc+0x4af/0x19a0 mm/slub.c:3540
  __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3625
  __slab_alloc_node mm/slub.c:3678 [inline]
  slab_alloc_node mm/slub.c:3850 [inline]
  kmem_cache_alloc_lru+0x379/0x6f0 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
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802f4fc780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802f4fc800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802f4fc880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88802f4fc900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802f4fc980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Fixes: 43815482 ("net: sock_def_readable() and friends RCU conversion")
Reported-and-tested-by: syzbot+32b89eaa102b372ff76d@syzkaller.appspotmail.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240126165532.3396702-1-edumazet@google.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>