syzbot

IPVS: stopping backup sync thread 12323 ...
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc1-syzkaller-00028-g5c8c229261f1 #0 Not tainted
------------------------------------------------------
syz.2.2818/12322 is trying to acquire lock:
ffffffff8fef49a8 (rtnl_mutex){+.+.}-{4:4}, at: ip_mc_drop_socket+0x9b/0x290 net/ipv4/igmp.c:2784

but task is already holding lock:
ffff8880233a2d28 (&smc->clcsock_release_lock){+.+.}-{4:4}, at: smc_setsockopt+0x101/0xa00 net/smc/af_smc.c:3073

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&smc->clcsock_release_lock){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
       smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:903
       smc_sendmsg+0x13d/0x520 net/smc/af_smc.c:2781
       sock_sendmsg_nosec net/socket.c:713 [inline]
       __sock_sendmsg net/socket.c:728 [inline]
       __sys_sendto+0x488/0x4f0 net/socket.c:2182
       __do_sys_sendto net/socket.c:2189 [inline]
       __se_sys_sendto net/socket.c:2185 [inline]
       __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2185
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sk_lock-AF_INET){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3645
       lock_sock include/net/sock.h:1624 [inline]
       sockopt_lock_sock net/core/sock.c:1133 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1124
       do_ip_getsockopt+0x1936/0x26e0 net/ipv4/ip_sockglue.c:1703
       ip_getsockopt+0x9c/0x1e0 net/ipv4/ip_sockglue.c:1765
       udp_getsockopt+0x61/0xb0 net/ipv4/udp.c:3122
       do_sock_getsockopt+0x3fe/0x800 net/socket.c:2359
       __sys_getsockopt+0x12f/0x260 net/socket.c:2388
       __do_sys_getsockopt net/socket.c:2395 [inline]
       __se_sys_getsockopt net/socket.c:2392 [inline]
       __x64_sys_getsockopt+0xbd/0x160 net/socket.c:2392
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (rtnl_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain kernel/locking/lockdep.c:3906 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
       ip_mc_drop_socket+0x9b/0x290 net/ipv4/igmp.c:2784
       inet_release+0xa3/0x280 net/ipv4/af_inet.c:422
       __sock_release net/socket.c:642 [inline]
       sock_release+0x8e/0x1d0 net/socket.c:670
       stop_sync_thread+0x285/0x720 net/netfilter/ipvs/ip_vs_sync.c:2004
       do_ip_vs_set_ctl+0x4ec/0x11c0 net/netfilter/ipvs/ip_vs_ctl.c:2734
       nf_setsockopt+0x8a/0xf0 net/netfilter/nf_sockopt.c:101
       ip_setsockopt+0xcb/0xf0 net/ipv4/ip_sockglue.c:1424
       tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4030
       smc_setsockopt+0x1b4/0xa00 net/smc/af_smc.c:3081
       do_sock_setsockopt+0x222/0x480 net/socket.c:2298
       __sys_setsockopt+0x1a0/0x230 net/socket.c:2323
       __do_sys_setsockopt net/socket.c:2329 [inline]
       __se_sys_setsockopt net/socket.c:2326 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2326
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  rtnl_mutex --> sk_lock-AF_INET --> &smc->clcsock_release_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&smc->clcsock_release_lock);
                               lock(sk_lock-AF_INET);
                               lock(&smc->clcsock_release_lock);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz.2.2818/12322:
 #0: ffff8880233a2d28 (&smc->clcsock_release_lock){+.+.}-{4:4}, at: smc_setsockopt+0x101/0xa00 net/smc/af_smc.c:3073

stack backtrace:
CPU: 1 UID: 0 PID: 12322 Comm: syz.2.2818 Not tainted 6.14.0-rc1-syzkaller-00028-g5c8c229261f1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain kernel/locking/lockdep.c:3906 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
 __mutex_lock_common kernel/locking/mutex.c:585 [inline]
 __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
 ip_mc_drop_socket+0x9b/0x290 net/ipv4/igmp.c:2784
 inet_release+0xa3/0x280 net/ipv4/af_inet.c:422
 __sock_release net/socket.c:642 [inline]
 sock_release+0x8e/0x1d0 net/socket.c:670
 stop_sync_thread+0x285/0x720 net/netfilter/ipvs/ip_vs_sync.c:2004
 do_ip_vs_set_ctl+0x4ec/0x11c0 net/netfilter/ipvs/ip_vs_ctl.c:2734
 nf_setsockopt+0x8a/0xf0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xcb/0xf0 net/ipv4/ip_sockglue.c:1424
 tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4030
 smc_setsockopt+0x1b4/0xa00 net/smc/af_smc.c:3081
 do_sock_setsockopt+0x222/0x480 net/socket.c:2298
 __sys_setsockopt+0x1a0/0x230 net/socket.c:2323
 __do_sys_setsockopt net/socket.c:2329 [inline]
 __se_sys_setsockopt net/socket.c:2326 [inline]
 __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2326
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f68fef8cde9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f68ffdf0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f68ff1a5fa0 RCX: 00007f68fef8cde9
RDX: 000000000000048c RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f68ff00e2a0 R08: 0000000000000018 R09: 0000000000000000
R10: 00002000000002c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f68ff1a5fa0 R15: 00007ffc896da238
 </TASK>