syzbot

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc6-syzkaller-00130-ga26ff37e624d #0 Not tainted
------------------------------------------------------
syz-executor.1/15929 is trying to acquire lock:
ffff88802f202af0 (clock-AF_INET6){++--}-{2:2}, at: sk_psock_drop+0x34/0x500 net/core/skmsg.c:837

but task is already holding lock:
ffff88801dc78260 (&htab->buckets[i].lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88801dc78260 (&htab->buckets[i].lock){+.-.}-{2:2}, at: sock_hash_delete_elem+0x17c/0x400 net/core/sock_map.c:945

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->buckets[i].lock){+.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:356 [inline]
       sock_hash_delete_elem+0x17c/0x400 net/core/sock_map.c:945
       bpf_prog_25e9489e9f218f49+0x2d/0x2d
       bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
       __bpf_prog_run include/linux/filter.h:657 [inline]
       bpf_prog_run include/linux/filter.h:664 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
       bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
       trace_kfree include/trace/events/kmem.h:94 [inline]
       kfree+0x2af/0x3a0 mm/slub.c:4377
       rds_send_remove_from_sock+0x66e/0x800 net/rds/send.c:666
       rds_send_path_drop_acked+0x36b/0x3b0 net/rds/send.c:709
       rds_tcp_write_space+0x196/0x5f0 net/rds/tcp_send.c:199
       tcp_new_space net/ipv4/tcp_input.c:5626 [inline]
       tcp_check_space+0x65e/0xb00 net/ipv4/tcp_input.c:5645
       tcp_data_snd_check net/ipv4/tcp_input.c:5654 [inline]
       tcp_rcv_established+0x111d/0x2020 net/ipv4/tcp_input.c:6081
       tcp_v6_do_rcv+0xa09/0x1300 net/ipv6/tcp_ipv6.c:1644
       sk_backlog_rcv include/net/sock.h:1106 [inline]
       __release_sock+0x1c8/0x350 net/core/sock.c:2984
       release_sock+0x61/0x1f0 net/core/sock.c:3550
       rds_send_xmit+0x1d3d/0x25b0 net/rds/send.c:421
       rds_send_worker+0x7d/0x2b0 net/rds/threads.c:200
       process_one_work kernel/workqueue.c:3267 [inline]
       process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3348
       worker_thread+0x86d/0xd70 kernel/workqueue.c:3429
       kthread+0x2f0/0x390 kernel/kthread.c:388
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (clock-AF_INET6){++--}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
       _raw_write_lock_bh+0x35/0x50 kernel/locking/spinlock.c:334
       sk_psock_drop+0x34/0x500 net/core/skmsg.c:837
       sock_hash_delete_elem+0x392/0x400 net/core/sock_map.c:949
       map_delete_elem+0x464/0x5e0 kernel/bpf/syscall.c:1696
       __sys_bpf+0x598/0x810 kernel/bpf/syscall.c:5651
       __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&htab->buckets[i].lock);
                               lock(clock-AF_INET6);
                               lock(&htab->buckets[i].lock);
  lock(clock-AF_INET6);

 *** DEADLOCK ***

2 locks held by syz-executor.1/15929:
 #0: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #0: ffffffff8e334da0 (rcu_read_lock){....}-{1:2}, at: map_delete_elem+0x388/0x5e0 kernel/bpf/syscall.c:1695
 #1: ffff88801dc78260 (&htab->buckets[i].lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #1: ffff88801dc78260 (&htab->buckets[i].lock){+.-.}-{2:2}, at: sock_hash_delete_elem+0x17c/0x400 net/core/sock_map.c:945

stack backtrace:
CPU: 1 PID: 15929 Comm: syz-executor.1 Not tainted 6.9.0-rc6-syzkaller-00130-ga26ff37e624d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
 _raw_write_lock_bh+0x35/0x50 kernel/locking/spinlock.c:334
 sk_psock_drop+0x34/0x500 net/core/skmsg.c:837
 sock_hash_delete_elem+0x392/0x400 net/core/sock_map.c:949
 map_delete_elem+0x464/0x5e0 kernel/bpf/syscall.c:1696
 __sys_bpf+0x598/0x810 kernel/bpf/syscall.c:5651
 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbae0c7dca9
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:00007fbae1a6f0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fbae0dabf80 RCX: 00007fbae0c7dca9
RDX: 0000000000000020 RSI: 0000000020000bc0 RDI: 0000000000000003
RBP: 00007fbae0cc947e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000004d R14: 00007fbae0dabf80 R15: 00007ffcddd705b8
 </TASK>