IPv4: Attempt to release TCP socket in state 8 00000000a1b8cf30 ========================= WARNING: held lock freed! syzkaller #0 Not tainted ------------------------- syz.0.8436/21960 is freeing memory ffff0000d95e6780-ffff0000d95e7267, with a lock still held there! ffff0000d95e68a0 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 2 locks held by syz.0.8436/21960: #0: ffff0000d95e68a0 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 #1: ffff800008007b00 ((&msk->sk.icsk_retransmit_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline] #1: ffff800008007b00 ((&msk->sk.icsk_retransmit_timer)){+.-.}-{0:0}, at: call_timer_fn+0xd0/0x850 kernel/time/timer.c:1638 stack backtrace: CPU: 0 PID: 21960 Comm: syz.0.8436 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/26/2026 Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_freed_lock_bug kernel/locking/lockdep.c:6401 [inline] debug_check_no_locks_freed+0x20c/0x29c kernel/locking/lockdep.c:6434 slab_free_hook mm/slub.c:1682 [inline] slab_free_freelist_hook+0x88/0x1e4 mm/slub.c:1736 slab_free mm/slub.c:3504 [inline] kmem_cache_free+0xdc/0x3b0 mm/slub.c:3520 sk_prot_free net/core/sock.c:1903 [inline] __sk_destruct+0x42c/0x610 net/core/sock.c:1991 sk_destruct net/core/sock.c:2006 [inline] __sk_free+0x320/0x430 net/core/sock.c:2017 sk_free+0x68/0xd4 net/core/sock.c:2028 sock_put include/net/sock.h:1989 [inline] mptcp_retransmit_timer+0x190/0x29c net/mptcp/protocol.c:2237 call_timer_fn+0x19c/0x850 kernel/time/timer.c:1648 expire_timers kernel/time/timer.c:1699 [inline] __run_timers+0xb34/0xd8c kernel/time/timer.c:1970 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1983 handle_softirqs+0x344/0xbe4 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline] invoke_softirq kernel/softirq.c:457 [inline] __irq_exit_rcu+0x240/0x43c kernel/softirq.c:659 irq_exit+0x14/0x88 kernel/softirq.c:683 handle_domain_irq+0x14c/0x1fc kernel/irq/irqdesc.c:711 gic_handle_irq+0x78/0x1b8 drivers/irqchip/irq-gic-v3.c:765 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:903 do_interrupt_handler+0x6c/0x88 arch/arm64/kernel/entry-common.c:267 el1_interrupt+0x30/0x58 arch/arm64/kernel/entry-common.c:454 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0xb8/0x14c kernel/locking/spinlock.c:194 __mod_timer+0xa98/0xb44 kernel/time/timer.c:1081 mod_timer+0x2c/0x3c kernel/time/timer.c:1137 sk_reset_timer+0x30/0xf4 net/core/sock.c:3145 mptcp_reset_rtx_timer net/mptcp/protocol.c:893 [inline] __mptcp_push_pending+0x57c/0x694 net/mptcp/protocol.c:1707 mptcp_sendmsg+0x14a8/0x19b0 net/mptcp/protocol.c:1890 inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x62c/0x940 net/socket.c:2445 ___sys_sendmsg+0x1f0/0x27c net/socket.c:2499 __sys_sendmsg net/socket.c:2528 [inline] __do_sys_sendmsg net/socket.c:2537 [inline] __se_sys_sendmsg net/socket.c:2535 [inline] __arm64_sys_sendmsg+0x1bc/0x278 net/socket.c:2535 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584