warning: `syz.0.0' uses wireless extensions which will stop working for Wi-Fi 7 hardware; use nl80211
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc1-syzkaller-00060-ga24588245776 #0 Not tainted
------------------------------------------------------
syz.0.0/5326 is trying to acquire lock:
ffffffff900fd3c8 (rtnl_mutex){+.+.}-{4:4}, at: smc_vlan_by_tcpsk+0x39b/0x4f0 net/smc/smc_core.c:1908

but task is already holding lock:
ffff888053598258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1615 [inline]
ffff888053598258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1644

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       lock_sock_nested+0x48/0x100 net/core/sock.c:3697
       do_ipv6_setsockopt+0xccd/0x3680 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0x5d/0x170 net/ipv6/ipv6_sockglue.c:993
       do_sock_setsockopt+0x3b1/0x710 net/socket.c:2296
       __sys_setsockopt net/socket.c:2321 [inline]
       __do_sys_setsockopt net/socket.c:2327 [inline]
       __se_sys_setsockopt net/socket.c:2324 [inline]
       __x64_sys_setsockopt+0x1ee/0x280 net/socket.c:2324
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (rtnl_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909
       __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       __mutex_lock_common kernel/locking/mutex.c:601 [inline]
       __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746
       smc_vlan_by_tcpsk+0x39b/0x4f0 net/smc/smc_core.c:1908
       __smc_connect+0x296/0x1920 net/smc/af_smc.c:1520
       smc_connect+0x868/0xde0 net/smc/af_smc.c:1696
       __sys_connect_file net/socket.c:2038 [inline]
       __sys_connect+0x28c/0x2d0 net/socket.c:2057
       __do_sys_connect net/socket.c:2063 [inline]
       __se_sys_connect net/socket.c:2060 [inline]
       __x64_sys_connect+0x7a/0x90 net/socket.c:2060
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET6);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_INET6);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz.0.0/5326:
 #0: ffff888053598258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1615 [inline]
 #0: ffff888053598258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1644

stack backtrace:
CPU: 0 UID: 0 PID: 5326 Comm: syz.0.0 Not tainted 6.15.0-rc1-syzkaller-00060-ga24588245776 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079
 check_noncircular+0x142/0x160 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909
 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746
 smc_vlan_by_tcpsk+0x39b/0x4f0 net/smc/smc_core.c:1908
 __smc_connect+0x296/0x1920 net/smc/af_smc.c:1520
 smc_connect+0x868/0xde0 net/smc/af_smc.c:1696
 __sys_connect_file net/socket.c:2038 [inline]
 __sys_connect+0x28c/0x2d0 net/socket.c:2057
 __do_sys_connect net/socket.c:2063 [inline]
 __se_sys_connect net/socket.c:2060 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2060
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc85698d169
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:00007fc8577cb038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fc856ba5fa0 RCX: 00007fc85698d169
RDX: 000000000000001c RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007fc856a0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc856ba5fa0 R15: 00007fff7308c038
 </TASK>