------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 3 PID: 10624 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Modules linked in: CPU: 3 UID: 0 PID: 10624 Comm: syz.4.1269 Not tainted 6.14.0-rc3-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Code: ff 89 de e8 68 58 f5 fc 84 db 0f 85 66 ff ff ff e8 bb 5d f5 fc c6 05 d7 63 86 0b 01 90 48 c7 c7 80 00 d3 8b e8 f7 96 b5 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 98 5d f5 fc 0f b6 1d b2 63 86 0b 31 RSP: 0018:ffffc90000708d90 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817a1229 RDX: ffff8880300ec880 RSI: ffffffff817a1236 RDI: 0000000000000001 RBP: ffff88802a09ddc8 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88802a09ddc8 R13: ffff88804614d000 R14: 0000000000000014 R15: 0000000000000000 FS: 00007ff85792f6c0(0000) GS:ffff88806a900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff85790df98 CR3: 000000002c2b0000 CR4: 0000000000352ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> __refcount_sub_and_test include/linux/refcount.h:275 [inline] __refcount_dec_and_test include/linux/refcount.h:307 [inline] refcount_dec_and_test include/linux/refcount.h:325 [inline] p9_req_put+0x1ec/0x250 net/9p/client.c:404 req_done+0x1e7/0x2f0 net/9p/trans_virtio.c:147 vring_interrupt drivers/virtio/virtio_ring.c:2715 [inline] vring_interrupt+0x31b/0x400 drivers/virtio/virtio_ring.c:2690 __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline] handle_irq arch/x86/kernel/irq.c:247 [inline] call_irq_handler arch/x86/kernel/irq.c:259 [inline] __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:285 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:278 </IRQ> <TASK> asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693 RIP: 0010:lock_is_held_type+0x107/0x150 kernel/locking/lockdep.c:5928 Code: 00 00 b8 ff ff ff ff 65 0f c1 05 3c 85 ab 74 83 f8 01 75 2d 9c 58 f6 c4 02 75 43 48 f7 04 24 00 02 00 00 74 01 fb 48 83 c4 08 <44> 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 45 31 ed eb RSP: 0018:ffffc90006fa7a18 EFLAGS: 00000286 RAX: 0000000000000046 RBX: 1ffff92000df4f4c RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8b6cef80 RDI: ffffffff8bd35380 RBP: ffffffff8e1bcc20 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880300ec880 R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000 lock_is_held include/linux/lockdep.h:249 [inline] __might_resched+0x473/0x5e0 kernel/sched/core.c:8729 __might_fault+0x83/0x190 mm/memory.c:6837 __copy_from_user include/linux/uaccess.h:106 [inline] check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline] __fpu_restore_sig+0xe3/0x1430 arch/x86/kernel/fpu/signal.c:349 fpu__restore_sig+0x113/0x190 arch/x86/kernel/fpu/signal.c:494 restore_sigcontext+0x4ca/0x6a0 arch/x86/kernel/signal_64.c:95 __do_sys_rt_sigreturn+0x1bd/0x240 arch/x86/kernel/signal_64.c:266 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff856b8cde7 Code: ff ff 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 a8 ff ff ff f7 d8 64 89 RSP: 002b:00007ff85792f038 EFLAGS: 00000246 RAX: 0000000000000120 RBX: 00007ff856da5fa0 RCX: 00007ff856b8cde9 RDX: 0000000000000000 RSI: 0000400000000900 RDI: 0000000000000005 RBP: 00007ff856c0e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000800 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff856da5fa0 R15: 00007ffdcc5551b8 </TASK> ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: b8 ff ff ff ff mov $0xffffffff,%eax 7: 65 0f c1 05 3c 85 ab xadd %eax,%gs:0x74ab853c(%rip) # 0x74ab854b e: 74 f: 83 f8 01 cmp $0x1,%eax 12: 75 2d jne 0x41 14: 9c pushf 15: 58 pop %rax 16: f6 c4 02 test $0x2,%ah 19: 75 43 jne 0x5e 1b: 48 f7 04 24 00 02 00 testq $0x200,(%rsp) 22: 00 23: 74 01 je 0x26 25: fb sti 26: 48 83 c4 08 add $0x8,%rsp * 2a: 44 89 e8 mov %r13d,%eax <-- trapping instruction 2d: 5b pop %rbx 2e: 5d pop %rbp 2f: 41 5c pop %r12 31: 41 5d pop %r13 33: 41 5e pop %r14 35: 41 5f pop %r15 37: c3 ret 38: cc int3 39: cc int3 3a: cc int3 3b: cc int3 3c: 45 31 ed xor %r13d,%r13d 3f: eb .byte 0xeb