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Eric Dumazet 4d322dce82 af_unix: fix lockdep positive in sk_diag_dump_icons() 
syzbot reported a lockdep splat [1].

Blamed commit hinted about the possible lockdep
violation, and code used unix_state_lock_nested()
in an attempt to silence lockdep.

It is not sufficient, because unix_state_lock_nested()
is already used from unix_state_double_lock().

We need to use a separate subclass.

This patch adds a distinct enumeration to make things
more explicit.

Also use swap() in unix_state_double_lock() as a clean up.

v2: add a missing inline keyword to unix_state_lock_nested()

[1]
WARNING: possible circular locking dependency detected
6.8.0-rc1-syzkaller-00356-g8a696a29c690 #0 Not tainted

syz-executor.1/2542 is trying to acquire lock:
 ffff88808b5df9e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: skb_queue_tail+0x36/0x120 net/core/skbuff.c:3863

but task is already holding lock:
 ffff88808b5dfe70 (&u->lock/1){+.+.}-{2:2}, at: unix_dgram_sendmsg+0xfc7/0x2200 net/unix/af_unix.c:2089

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&u->lock/1){+.+.}-{2:2}:
        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
        _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
        sk_diag_dump_icons net/unix/diag.c:87 [inline]
        sk_diag_fill+0x6ea/0xfe0 net/unix/diag.c:157
        sk_diag_dump net/unix/diag.c:196 [inline]
        unix_diag_dump+0x3e9/0x630 net/unix/diag.c:220
        netlink_dump+0x5c1/0xcd0 net/netlink/af_netlink.c:2264
        __netlink_dump_start+0x5d7/0x780 net/netlink/af_netlink.c:2370
        netlink_dump_start include/linux/netlink.h:338 [inline]
        unix_diag_handler_dump+0x1c3/0x8f0 net/unix/diag.c:319
       sock_diag_rcv_msg+0xe3/0x400
        netlink_rcv_skb+0x1df/0x430 net/netlink/af_netlink.c:2543
        sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:280
        netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
        netlink_unicast+0x7e6/0x980 net/netlink/af_netlink.c:1367
        netlink_sendmsg+0xa37/0xd70 net/netlink/af_netlink.c:1908
        sock_sendmsg_nosec net/socket.c:730 [inline]
        __sock_sendmsg net/socket.c:745 [inline]
        sock_write_iter+0x39a/0x520 net/socket.c:1160
        call_write_iter include/linux/fs.h:2085 [inline]
        new_sync_write fs/read_write.c:497 [inline]
        vfs_write+0xa74/0xca0 fs/read_write.c:590
        ksys_write+0x1a0/0x2c0 fs/read_write.c:643
        do_syscall_x64 arch/x86/entry/common.c:52 [inline]
        do_syscall_64+0xf5/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #0 (rlock-AF_UNIX){+.+.}-{2:2}:
        check_prev_add kernel/locking/lockdep.c:3134 [inline]
        check_prevs_add kernel/locking/lockdep.c:3253 [inline]
        validate_chain+0x1909/0x5ab0 kernel/locking/lockdep.c:3869
        __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
        _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
        skb_queue_tail+0x36/0x120 net/core/skbuff.c:3863
        unix_dgram_sendmsg+0x15d9/0x2200 net/unix/af_unix.c:2112
        sock_sendmsg_nosec net/socket.c:730 [inline]
        __sock_sendmsg net/socket.c:745 [inline]
        ____sys_sendmsg+0x592/0x890 net/socket.c:2584
        ___sys_sendmsg net/socket.c:2638 [inline]
        __sys_sendmmsg+0x3b2/0x730 net/socket.c:2724
        __do_sys_sendmmsg net/socket.c:2753 [inline]
        __se_sys_sendmmsg net/socket.c:2750 [inline]
        __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2750
        do_syscall_x64 arch/x86/entry/common.c:52 [inline]
        do_syscall_64+0xf5/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&u->lock/1);
                               lock(rlock-AF_UNIX);
                               lock(&u->lock/1);
  lock(rlock-AF_UNIX);

 *** DEADLOCK ***

1 lock held by syz-executor.1/2542:
  #0: ffff88808b5dfe70 (&u->lock/1){+.+.}-{2:2}, at: unix_dgram_sendmsg+0xfc7/0x2200 net/unix/af_unix.c:2089

stack backtrace:
CPU: 1 PID: 2542 Comm: syz-executor.1 Not tainted 6.8.0-rc1-syzkaller-00356-g8a696a29c690 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
  check_noncircular+0x366/0x490 kernel/locking/lockdep.c:2187
  check_prev_add kernel/locking/lockdep.c:3134 [inline]
  check_prevs_add kernel/locking/lockdep.c:3253 [inline]
  validate_chain+0x1909/0x5ab0 kernel/locking/lockdep.c:3869
  __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
  lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
  _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
  skb_queue_tail+0x36/0x120 net/core/skbuff.c:3863
  unix_dgram_sendmsg+0x15d9/0x2200 net/unix/af_unix.c:2112
  sock_sendmsg_nosec net/socket.c:730 [inline]
  __sock_sendmsg net/socket.c:745 [inline]
  ____sys_sendmsg+0x592/0x890 net/socket.c:2584
  ___sys_sendmsg net/socket.c:2638 [inline]
  __sys_sendmmsg+0x3b2/0x730 net/socket.c:2724
  __do_sys_sendmmsg net/socket.c:2753 [inline]
  __se_sys_sendmmsg net/socket.c:2750 [inline]
  __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2750
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xf5/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f26d887cda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f26d95a60c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f26d89abf80 RCX: 00007f26d887cda9
RDX: 000000000000003e RSI: 00000000200bd000 RDI: 0000000000000004
RBP: 00007f26d88c947a R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000008c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f26d89abf80 R15: 00007ffcfe081a68

Fixes: 2aac7a2cb0 ("unix_diag: Pending connections IDs NLA")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240130184235.1620738-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 		2024-01-31 17:51:55 -08:00
..
6lowpan
…
9p net: 9p: avoid freeing uninit memory in p9pdu_vreadf 2023-12-13 05:44:30 +09:00
802
…
8021q vlan: skip nested type that is not IFLA_VLAN_QOS_MAPPING 2024-01-19 21:25:06 -08:00
appletalk net: remove SOCK_DEBUG leftovers 2023-12-26 20:31:01 +00:00
atm net: fill in MODULE_DESCRIPTION()s for ATM 2024-01-05 08:04:23 -08:00
ax25
…
batman-adv batman-adv: Switch to linux/array_size.h 2023-11-14 08:16:34 +01:00
bluetooth TTY/Serial changes for 6.8-rc1 2024-01-18 11:37:24 -08:00
bpf bpf: Fix dtor CFI 2023-12-15 16:25:55 -08:00
bridge bridge: mcast: fix disabled snooping after long uptime 2024-01-30 18:06:56 -08:00
caif net: fill in MODULE_DESCRIPTION()s for CAIF 2024-01-05 08:06:35 -08:00
can
…
ceph libceph: remove MAX_EXTENTS check for sparse reads 2024-01-15 15:40:50 +01:00
core xdp: reflect tail increase for MEM_TYPE_XSK_BUFF_POOL 2024-01-24 16:24:07 -08:00
dcb
…
dccp net: remove SOCK_DEBUG leftovers 2023-12-26 20:31:01 +00:00
devlink devlink: Fix referring to hw_addr attribute during state validation 2024-01-30 18:32:41 -08:00
dns_resolver Networking changes for 6.8. 2024-01-11 10:07:29 -08:00
dsa net: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events 2024-01-11 16:33:52 -08:00
ethernet
…
ethtool ethtool: netlink: Add missing ethnl_ops_begin/complete 2024-01-18 13:21:06 +01:00
handshake
…
hsr net: hsr: remove WARN_ONCE() in send_hsr_supervision_frame() 2024-01-29 11:29:55 +00:00
ieee802154 mac802154: Avoid new associations while disassociating 2023-12-15 11:14:57 +01:00
ife net: sched: ife: fix potential use-after-free 2023-12-15 10:50:18 +00:00
ipv4 net: ipv4: fix a memleak in ip_setup_cork 2024-01-31 15:53:25 -08:00
ipv6 ipv6: Ensure natural alignment of const ipv6 loopback and router addresses 2024-01-30 12:43:18 +01:00
iucv iucv: make iucv_bus const 2023-12-29 07:46:38 +00:00
kcm net: kcm: fix direct access to bv_len 2024-01-03 18:37:22 -08:00
key
…
l2tp ipv6: annotate data-races around np->ucast_oif 2023-12-11 10:59:17 +00:00
l3mdev
…
lapb
…
llc llc: call sock_orphan() at release time 2024-01-30 13:49:09 +01:00
mac80211 wireless fixes for v6.8-rc2 2024-01-23 08:38:13 -08:00
mac802154 mac802154: Avoid new associations while disassociating 2023-12-15 11:14:57 +01:00
mctp
…
mpls
…
mptcp mptcp: relax check on MPC passive fallback 2024-01-17 10:55:54 +00:00
ncsi net/ncsi: Add NC-SI 1.2 Get MC MAC Address command 2023-11-18 15:00:51 +00:00
netfilter netfilter: nf_tables: validate NFPROTO_* family 2024-01-24 20:02:40 +01:00
netlabel calipso: fix memory leak in netlbl_calipso_add_pass() 2023-12-07 14:23:12 -05:00
netlink netlink: fix potential sleeping issue in mqueue_flush_file 2024-01-23 11:21:18 +01:00
netrom
…
nfc nfc: nci: free rx_data_reassembly skb on NCI device cleanup 2024-01-29 12:05:31 +00:00
nsh
…
openvswitch net/sched: act_ct: Always fill offloading tuple iifidx 2023-11-08 17:47:08 -08:00
packet net: fill in MODULE_DESCRIPTION() for AF_PACKET 2024-01-05 08:06:35 -08:00
phonet
…
psample genetlink: Use internal flags for multicast groups 2023-12-29 08:43:59 +00:00
qrtr net: qrtr: ns: Return 0 if server port is not present 2024-01-01 18:41:29 +00:00
rds net/rds: Fix UBSAN: array-index-out-of-bounds in rds_cmsg_recv 2024-01-22 11:24:00 +00:00
rfkill Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-12-21 22:17:23 +01:00
rose net/rose: fix races in rose_kill_by_device() 2023-12-15 11:59:53 +00:00
rxrpc rxrpc: Fix use of Don't Fragment flag 2024-01-11 16:41:41 -08:00
sched net/sched: flower: Fix chain template offload 2024-01-24 01:33:59 +00:00
sctp sctp: fix busy polling 2024-01-04 10:29:18 +00:00
smc net/smc: fix incorrect SMC-D link group matching logic 2024-01-26 14:06:05 -08:00
strparser
…
sunrpc nfsd-6.8 fixes: 2024-01-25 10:26:52 -08:00
switchdev
…
tipc tipc: Remove some excess struct member documentation 2023-12-22 23:14:43 +00:00
tls net: tls, fix WARNIING in __sk_msg_free 2024-01-14 12:17:14 +00:00
unix af_unix: fix lockdep positive in sk_diag_dump_icons() 2024-01-31 17:51:55 -08:00
vmw_vsock vsock/virtio: use skb_frag_*() helpers 2024-01-03 18:37:16 -08:00
wireless wireless fixes for v6.8-rc2 2024-01-23 08:38:13 -08:00
x25 net: remove SOCK_DEBUG leftovers 2023-12-26 20:31:01 +00:00
xdp xsk: make xsk_buff_pool responsible for clearing xdp_buff::flags 2024-01-24 16:24:06 -08:00
xfrm bpf: xfrm: Add bpf_xdp_get_xfrm_state() kfunc 2023-12-14 17:12:49 -08:00
Kconfig bpfilter: remove bpfilter 2024-01-04 10:23:10 -08:00
Kconfig.debug
…
Makefile bpfilter: remove bpfilter 2024-01-04 10:23:10 -08:00
compat.c file: stop exposing receive_fd_user() 2023-12-12 14:24:14 +01:00
devres.c
…
socket.c vfs-6.8.iov_iter 2024-01-08 11:43:04 -08:00
sysctl_net.c
…