------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 19479 at lib/refcount.c:28 refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 Modules linked in: CPU: 0 PID: 19479 Comm: syz-executor.0 Not tainted 5.10.49 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 RIP: 0010:refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 Code: 1d a4 a2 54 03 31 ff 89 de e8 69 69 51 ff 84 db 75 a3 e8 30 70 51 ff 48 c7 c7 e0 33 3b 84 c6 05 84 a2 54 03 01 e8 b9 a4 c8 01 <0f> 0b eb 87 e8 14 70 51 ff 0f b6 1d 6d a2 54 03 31 ff 89 de e8 34 RSP: 0018:ffff88805a6af9f8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff81293b93 RDI: ffffed100b4d5f31 RBP: ffff888057e4305c R08: 0000000000000001 R09: ffff88806ce2facf R10: 0000000000000000 R11: 0000000000000001 R12: ffff888057e4305c R13: 0000000000002844 R14: ffff888057e43198 R15: 0000000000000000 FS: 00007f7b95f27700(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2de23000 CR3: 0000000058720000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: __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] io_put_req+0xc6/0x100 fs/io_uring.c:2220 __io_queue_sqe+0x1df/0xd00 fs/io_uring.c:6365 io_queue_sqe+0x5bc/0x1020 fs/io_uring.c:6410 io_queue_link_head fs/io_uring.c:6421 [inline] io_submit_sqe fs/io_uring.c:6462 [inline] io_submit_sqes+0x176b/0x2300 fs/io_uring.c:6707 __do_sys_io_uring_enter+0x1092/0x1910 fs/io_uring.c:9100 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x466609 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:00007f7b95f27188 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 0000000000466609 RDX: 0000000000000000 RSI: 00000000000076d3 RDI: 0000000000000003 RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffce8175a2f R14: 00007f7b95f27300 R15: 0000000000022000 irq event stamp: 1587 hardirqs last enabled at (1599): [] console_unlock+0x929/0xb30 kernel/printk/printk.c:2552 hardirqs last disabled at (1610): [] console_unlock+0x835/0xb30 kernel/printk/printk.c:2467 softirqs last enabled at (1560): [] asm_call_irq_on_stack+0x12/0x20 softirqs last disabled at (1555): [] asm_call_irq_on_stack+0x12/0x20 ---[ end trace 2ace85296b72bded ]--- audit: type=1400 audit(1626657866.694:62): avc: denied { relabelto } for pid=19500 comm="syz-executor.6" name="UDPv6" dev="sockfs" ino=48748 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:fonts_t:s0 tclass=udp_socket permissive=1