====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/5791 is trying to acquire lock: ffff888061daf7a0 (&htab->lockdep_key#2){-.-.}-{2:2}, at: htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 but task is already holding lock: ffff88801e26b7a0 (&htab->lockdep_key){-.-.}-{2:2}, at: htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&htab->lockdep_key){-.-.}-{2:2}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:612 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122 trace_contention_end+0xe6/0x110 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7ec/0x9d0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:612 [inline] bpf_prog_run include/linux/filter.h:619 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:636 [inline] bpf_flow_dissect+0x12f/0x3e0 net/core/flow_dissector.c:1000 bpf_prog_test_run_flow_dissector+0x40d/0x600 net/bpf/test_run.c:1353 bpf_prog_test_run+0x321/0x390 kernel/bpf/syscall.c:4129 __sys_bpf+0x440/0x800 kernel/bpf/syscall.c:5491 __do_sys_bpf kernel/bpf/syscall.c:5577 [inline] __se_sys_bpf kernel/bpf/syscall.c:5575 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5575 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&htab->lockdep_key#2){-.-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:605 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x312/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122 trace_contention_end+0xe6/0x110 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7ec/0x9d0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:605 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x312/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122 trace_contention_end+0xc5/0xe0 include/trace/events/lock.h:122 __mutex_lock_common kernel/locking/mutex.c:612 [inline] __mutex_lock+0x2fa/0xcc0 kernel/locking/mutex.c:747 nf_sockopt_find net/netfilter/nf_sockopt.c:67 [inline] nf_getsockopt+0x34/0x280 net/netfilter/nf_sockopt.c:113 ipv6_getsockopt+0x216/0x2c0 net/ipv6/ipv6_sockglue.c:1499 do_sock_getsockopt+0x368/0x440 net/socket.c:2384 __sys_getsockopt net/socket.c:2413 [inline] __do_sys_getsockopt net/socket.c:2423 [inline] __se_sys_getsockopt net/socket.c:2420 [inline] __x64_sys_getsockopt+0x1d6/0x280 net/socket.c:2420 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&htab->lockdep_key); lock(&htab->lockdep_key#2); lock(&htab->lockdep_key); lock(&htab->lockdep_key#2); *** DEADLOCK *** 4 locks held by syz-executor/5791: #0: ffffffff8e0289e8 (nf_sockopt_mutex){+.+.}-{3:3}, at: nf_sockopt_find net/netfilter/nf_sockopt.c:67 [inline] #0: ffffffff8e0289e8 (nf_sockopt_mutex){+.+.}-{3:3}, at: nf_getsockopt+0x34/0x280 net/netfilter/nf_sockopt.c:113 #1: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #1: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #1: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #1: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361 #2: ffff88801e26b7a0 (&htab->lockdep_key){-.-.}-{2:2}, at: htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 #3: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #3: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #3: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline] #3: ffffffff8cd2fee0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361 stack backtrace: CPU: 1 PID: 5791 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106 check_noncircular+0x2bd/0x3c0 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 kernel/locking/lockdep.c:3869 [inline] __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:605 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x312/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122 trace_contention_end+0xe6/0x110 include/trace/events/lock.h:122 __pv_queued_spin_lock_slowpath+0x7ec/0x9d0 kernel/locking/qspinlock.c:560 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115 htab_lock_bucket+0x181/0x300 kernel/bpf/hashtab.c:166 htab_lru_map_delete_elem+0x1a4/0x630 kernel/bpf/hashtab.c:1479 bpf_prog_2c29ac5cdc6b1842+0x42/0x46 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline] __bpf_prog_run include/linux/filter.h:605 [inline] bpf_prog_run include/linux/filter.h:619 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline] bpf_trace_run2+0x312/0x3c0 kernel/trace/bpf_trace.c:2361 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122 trace_contention_end+0xc5/0xe0 include/trace/events/lock.h:122 __mutex_lock_common kernel/locking/mutex.c:612 [inline] __mutex_lock+0x2fa/0xcc0 kernel/locking/mutex.c:747 nf_sockopt_find net/netfilter/nf_sockopt.c:67 [inline] nf_getsockopt+0x34/0x280 net/netfilter/nf_sockopt.c:113 ipv6_getsockopt+0x216/0x2c0 net/ipv6/ipv6_sockglue.c:1499 do_sock_getsockopt+0x368/0x440 net/socket.c:2384 __sys_getsockopt net/socket.c:2413 [inline] __do_sys_getsockopt net/socket.c:2423 [inline] __se_sys_getsockopt net/socket.c:2420 [inline] __x64_sys_getsockopt+0x1d6/0x280 net/socket.c:2420 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f840339140a Code: ff c3 66 0f 1f 44 00 00 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb b8 0f 1f 44 00 00 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 a8 ff ff ff f7 RSP: 002b:00007fffcf903bb8 EFLAGS: 00000242 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 00007fffcf903be0 RCX: 00007f840339140a RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003 RBP: 0000000000000003 R08: 00007fffcf903bdc R09: 0079746972756365 R10: 00007fffcf903be0 R11: 0000000000000242 R12: 00007f84035b3a20 R13: 00007fffcf903bdc R14: 0000000000000000 R15: 00007f84035b4e60