syzbot

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc2-syzkaller-00291-g09f6b0c8904b #0 Not tainted
------------------------------------------------------
syz.3.3901/27802 is trying to acquire lock:
ffffffff8fac34a8 (rtnl_mutex){+.+.}-{3:3}, at: ip_mroute_setsockopt+0x121/0x15c0 net/ipv4/ipmr.c:1370

but task is already holding lock:
ffff88807c787228 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x101/0xc00 net/smc/af_smc.c:3056

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&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:2771
       sock_sendmsg_nosec net/socket.c:729 [inline]
       __sock_sendmsg net/socket.c:744 [inline]
       ____sys_sendmsg+0x9ae/0xb40 net/socket.c:2607
       ___sys_sendmsg+0x135/0x1e0 net/socket.c:2661
       __sys_sendmsg+0x117/0x1f0 net/socket.c:2690
       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_INET6){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3611
       lock_sock include/net/sock.h:1611 [inline]
       sockopt_lock_sock net/core/sock.c:1125 [inline]
       sockopt_lock_sock+0x54/0x70 net/core/sock.c:1116
       do_ip_setsockopt+0x101/0x38c0 net/ipv4/ip_sockglue.c:1078
       ip_setsockopt+0x59/0xf0 net/ipv4/ip_sockglue.c:1417
       ipv6_setsockopt+0x155/0x170 net/ipv6/ipv6_sockglue.c:988
       sctp_setsockopt+0x16a/0xb880 net/sctp/socket.c:4587
       do_sock_setsockopt+0x222/0x480 net/socket.c:2334
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2357
       __do_sys_setsockopt net/socket.c:2366 [inline]
       __se_sys_setsockopt net/socket.c:2363 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2363
       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){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       ip_mroute_setsockopt+0x121/0x15c0 net/ipv4/ipmr.c:1370
       do_ip_setsockopt+0x2e7/0x38c0 net/ipv4/ip_sockglue.c:948
       ip_setsockopt+0x59/0xf0 net/ipv4/ip_sockglue.c:1417
       tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4029
       smc_setsockopt+0x1b4/0xc00 net/smc/af_smc.c:3064
       do_sock_setsockopt+0x222/0x480 net/socket.c:2334
       __sys_setsockopt+0x1a4/0x270 net/socket.c:2357
       __do_sys_setsockopt net/socket.c:2366 [inline]
       __se_sys_setsockopt net/socket.c:2363 [inline]
       __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2363
       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_INET6 --> &smc->clcsock_release_lock

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz.3.3901/27802:
 #0: ffff88807c787228 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_setsockopt+0x101/0xc00 net/smc/af_smc.c:3056

stack backtrace:
CPU: 0 UID: 0 PID: 27802 Comm: syz.3.3901 Not tainted 6.12.0-rc2-syzkaller-00291-g09f6b0c8904b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
 ip_mroute_setsockopt+0x121/0x15c0 net/ipv4/ipmr.c:1370
 do_ip_setsockopt+0x2e7/0x38c0 net/ipv4/ip_sockglue.c:948
 ip_setsockopt+0x59/0xf0 net/ipv4/ip_sockglue.c:1417
 tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4029
 smc_setsockopt+0x1b4/0xc00 net/smc/af_smc.c:3064
 do_sock_setsockopt+0x222/0x480 net/socket.c:2334
 __sys_setsockopt+0x1a4/0x270 net/socket.c:2357
 __do_sys_setsockopt net/socket.c:2366 [inline]
 __se_sys_setsockopt net/socket.c:2363 [inline]
 __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2363
 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: 0033:0x7f499f57dff9
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:00007f49a043f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f499f735f80 RCX: 00007f499f57dff9
RDX: 00100000000000c8 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f499f5f0296 R08: 0000000000000028 R09: 0000000000000000
R10: ffffffffff600000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f499f735f80 R15: 00007ffea386edc8
 </TASK>