------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 2966 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 2966 Comm: syz-executor.4 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28
Code: e9 db fe ff ff 48 89 df e8 7c 1a e8 fd e9 8a fe ff ff e8 62 5c a2 fd 48 c7 c7 00 2f e3 89 c6 05 39 b6 03 0a 01 e8 dc 73 0c 05 <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55
RSP: 0018:ffffc90000dc0d00 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8880809e54c0 RSI: ffffffff815d7275 RDI: fffff520001b8192
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815d10de R11: 0000000000000000 R12: ffff888033b96820
R13: 1ffff920001b81a8 R14: ffffffff8844ed50 R15: 0000000000000000
FS:  00007f1f80c9d700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020008038 CR3: 0000000149168000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 sctp_transport_put+0x138/0x180 net/sctp/transport.c:473
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1431
 expire_timers kernel/time/timer.c:1476 [inline]
 __run_timers.part.0+0x675/0xa50 kernel/time/timer.c:1745
 __run_timers kernel/time/timer.c:1726 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1758
 __do_softirq+0x29b/0x9bd kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:finish_task_switch.isra.0+0x23c/0xa50 kernel/sched/core.c:4557
Code: 8b 3a 4c 89 e7 48 c7 02 00 00 00 00 ff d1 4d 85 ff 75 bf 4c 89 e7 e8 13 49 d4 07 e8 4e cc 2b 00 fb 65 48 8b 1c 25 00 f0 01 00 <48> 8d bb 10 15 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1
RSP: 0018:ffffc900198af620 EFLAGS: 00000202
RAX: 0000000000001d91 RBX: ffff8880809e54c0 RCX: 1ffffffff2095552
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900198af660 R08: 0000000000000001 R09: ffffffff9049d8c7
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8880b9d35a40
R13: ffff88801dccb880 R14: 0000000000000000 R15: ffff8880b9d35a58
 context_switch kernel/sched/core.c:4686 [inline]
 __schedule+0x93c/0x2710 kernel/sched/core.c:5940
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6328
 irqentry_exit+0x31/0x80 kernel/entry/common.c:427
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:get_vma_policy mm/mempolicy.c:1832 [inline]
RIP: 0010:get_vma_policy mm/mempolicy.c:1826 [inline]
RIP: 0010:alloc_pages_vma+0x147/0x770 mm/mempolicy.c:2183
Code: 66 45 85 e4 74 0d e8 38 de bc ff 48 89 ef e8 20 9c ff ff e8 2b de bc ff 4c 89 f8 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 <e8> 14 de bc ff 48 b8 00 00 00 00 00 fc ff df 65 48 8b 2c 25 00 f0
RSP: 0018:ffffc900198af818 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc90012ca9000
RDX: 0000000000040000 RSI: ffffffff81b8a602 RDI: ffff88802a7b17f0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81a9a774 R11: 0000000000000000 R12: 0000000001100dca
R13: ffff88802a7b1738 R14: 0000000000000000 R15: 0000000020008000
 wp_page_copy+0x1011/0x2450 mm/memory.c:2901
 do_wp_page+0x2cb/0x1ad0 mm/memory.c:3216
 handle_pte_fault mm/memory.c:4438 [inline]
 __handle_mm_fault+0x2a7d/0x5320 mm/memory.c:4555
 handle_mm_fault+0x1c8/0x7f0 mm/memory.c:4653
 do_user_addr_fault+0x483/0x1210 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
RIP: 0010:__put_user_nocheck_4+0x3/0x11
Code: 00 00 48 39 d9 73 54 0f 1f 00 66 89 01 31 c9 0f 1f 00 c3 0f 1f 44 00 00 48 bb fd ef ff ff ff 7f 00 00 48 39 d9 73 34 0f 1f 00 <89> 01 31 c9 0f 1f 00 c3 66 0f 1f 44 00 00 48 bb f9 ef ff ff ff 7f
RSP: 0018:ffffc900198afce8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00007fffffffeffd RCX: 0000000020008038
RDX: 0000000000040000 RSI: ffffffff8709dec2 RDI: 0000000000000000
RBP: 0000000000040000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000088 R12: 0000000000000001
R13: 0000000020008000 R14: 0000000000000070 R15: 000000000000006f
 __sys_sendmmsg+0x1cf/0x470 net/socket.c:2530
 __do_sys_sendmmsg net/socket.c:2554 [inline]
 __se_sys_sendmmsg net/socket.c:2551 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2551
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1f80c9d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0400000000000070 RSI: 0000000020007fc0 RDI: 0000000000000004
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 0000000000a9fb1f R14: 00007f1f80c9d300 R15: 0000000000022000