syzbot

======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc6-syzkaller-00363-g89f5e14d05b4 #0 Not tainted
------------------------------------------------------
syz.3.1530/10293 is trying to acquire lock:
ffff88807b975d58 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline]
ffff88807b975d58 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1061 [inline]
ffff88807b975d58 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sockopt_lock_sock+0x54/0x70 net/core/sock.c:1052

but task is already holding lock:
ffffffff8fa35ba8 (rtnl_mutex){+.+.}-{3:3}, at: do_ipv6_setsockopt+0x214f/0x4790 net/ipv6/ipv6_sockglue.c:566

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (rtnl_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       start_sync_thread+0x134/0x28e0 net/netfilter/ipvs/ip_vs_sync.c:1761
       do_ip_vs_set_ctl+0x452/0x11c0 net/netfilter/ipvs/ip_vs_ctl.c:2732
       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:3768
       smc_setsockopt+0x1b4/0xa00 net/smc/af_smc.c:3072
       do_sock_setsockopt+0x222/0x480 net/socket.c:2324
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2347
       __do_sys_setsockopt net/socket.c:2356 [inline]
       __se_sys_setsockopt net/socket.c:2353 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2353
       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 (&smc->clcsock_release_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       smc_switch_to_fallback+0x2d/0xa00 net/smc/af_smc.c:902
       smc_sendmsg+0x13d/0x520 net/smc/af_smc.c:2779
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg net/socket.c:745 [inline]
       __sys_sendto+0x47f/0x4e0 net/socket.c:2204
       __do_sys_sendto net/socket.c:2216 [inline]
       __se_sys_sendto net/socket.c:2212 [inline]
       __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2212
       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 (sk_lock-AF_INET6){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3133 [inline]
       check_prevs_add kernel/locking/lockdep.c:3252 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142
       lock_acquire kernel/locking/lockdep.c:5759 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3543
       lock_sock include/net/sock.h:1607 [inline]
       sockopt_lock_sock net/core/sock.c:1061 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1052
       do_ipv6_setsockopt+0x2157/0x4790 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0xe3/0x1a0 net/ipv6/ipv6_sockglue.c:993
       tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:3768
       do_sock_setsockopt+0x222/0x480 net/socket.c:2324
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2347
       __do_sys_setsockopt net/socket.c:2356 [inline]
       __se_sys_setsockopt net/socket.c:2353 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2353
       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:
  sk_lock-AF_INET6 --> &smc->clcsock_release_lock --> rtnl_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(rtnl_mutex);
                               lock(&smc->clcsock_release_lock);
                               lock(rtnl_mutex);
  lock(sk_lock-AF_INET6);

 *** DEADLOCK ***

1 lock held by syz.3.1530/10293:
 #0: ffffffff8fa35ba8 (rtnl_mutex){+.+.}-{3:3}
, at: do_ipv6_setsockopt+0x214f/0x4790 net/ipv6/ipv6_sockglue.c:566

stack backtrace:
CPU: 0 UID: 0 PID: 10293 Comm: syz.3.1530 Not tainted 6.11.0-rc6-syzkaller-00363-g89f5e14d05b4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2186
 check_prev_add kernel/locking/lockdep.c:3133 [inline]
 check_prevs_add kernel/locking/lockdep.c:3252 [inline]
 validate_chain kernel/locking/lockdep.c:3868 [inline]
 __lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142
 lock_acquire kernel/locking/lockdep.c:5759 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724
 lock_sock_nested+0x3a/0xf0 net/core/sock.c:3543
 lock_sock include/net/sock.h:1607 [inline]
 sockopt_lock_sock net/core/sock.c:1061 [inline]
 sockopt_lock_sock+0x54/0x70 net/core/sock.c:1052
 do_ipv6_setsockopt+0x2157/0x4790 net/ipv6/ipv6_sockglue.c:567
 ipv6_setsockopt+0xe3/0x1a0 net/ipv6/ipv6_sockglue.c:993
 tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:3768
 do_sock_setsockopt+0x222/0x480 net/socket.c:2324
 __sys_setsockopt+0x1a4/0x270 net/socket.c:2347
 __do_sys_setsockopt net/socket.c:2356 [inline]
 __se_sys_setsockopt net/socket.c:2353 [inline]
 __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2353
 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: 0033:0x7f938837cef9
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:00007f9389101038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f9388536058 RCX: 00007f938837cef9
RDX: 000000000000001b RSI: 0000000000000029 RDI: 0000000000000008
RBP: 00007f93883ef046 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9388536058 R15: 00007fff58334748
 </TASK>