------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 6828 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 3 UID: 0 PID: 6828 Comm: rm Not tainted 6.15.0-rc1-syzkaller-00246-g900241a5cc15 #0 PREEMPT(full) 
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 08 ab eb fc 84 db 0f 85 66 ff ff ff e8 1b b0 eb fc c6 05 5e 26 9f 0b 01 90 48 c7 c7 40 0f f4 8b e8 f7 40 ab fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 f8 af eb fc 0f b6 1d 39 26 9f 0b 31
RSP: 0018:ffffc900006f8d90 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817acff8
RDX: ffff88802471a440 RSI: ffffffff817ad005 RDI: 0000000000000001
RBP: ffff88804e46e118 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88804e46e118
R13: ffff88802a1edc00 R14: 0000000000000015 R15: 1ffff110209f380c
FS:  0000000000000000(0000) GS:ffff8880d6cb3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8fe2a47108 CR3: 00000000518ec000 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:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 p9_req_put+0x1ec/0x250 net/9p/client.c:404
 req_done+0x1dc/0x2e0 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:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:266 [inline]
 __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:stack_depot_save_flags+0x4/0xa50 lib/stackdepot.c:599
Code: 01 0f 85 10 ff ff ff 90 0f 0b 90 e9 07 ff ff ff 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <83> f9 03 0f 87 96 03 00 00 41 57 41 56 49 89 fe 41 55 41 54 41 89
RSP: 0018:ffffc9000392f5d0 EFLAGS: 00000283
RAX: 000000000000000d RBX: ffffc9000392f5d8 RCX: 0000000000000001
RDX: 0000000000000cc0 RSI: 000000000000000d RDI: ffffc9000392f5d8
RBP: 0000000000000cc0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000cc0 R14: 0000000000000100 R15: 0000000000000000
 kasan_save_stack+0x42/0x60 mm/kasan/common.c:48
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4151 [inline]
 slab_alloc_node mm/slub.c:4200 [inline]
 kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4207
 vm_area_alloc+0x1f/0x160 kernel/fork.c:441
 __mmap_new_vma mm/vma.c:2359 [inline]
 __mmap_region+0xfd0/0x27c0 mm/vma.c:2476
 mmap_region+0x1ab/0x3f0 mm/vma.c:2554
 do_mmap+0xd8e/0x11b0 mm/mmap.c:561
 vm_mmap_pgoff+0x281/0x450 mm/util.c:579
 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8fe2a71b74
Code: 63 08 44 89 e8 5b 41 5c 41 5d c3 41 89 ca 41 f7 c1 ff 0f 00 00 74 0c c7 05 f5 46 01 00 16 00 00 00 eb 17 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 0c f7 d8 89 05 dc 46 01 00 48 83 c8 ff c3 0f
RSP: 002b:00007ffeae8187d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007ffeae818888 RCX: 00007f8fe2a71b74
RDX: 0000000000000003 RSI: 0000000000006000 RDI: 00007f8fe2976000
RBP: 00007ffeae818f70 R08: 0000000000000003 R09: 000000000019d000
R10: 0000000000000812 R11: 0000000000000246 R12: 00007f8fe2a4c8d0
R13: 00007ffeae818ff8 R14: 000000000019d264 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	0f 85 10 ff ff ff    	jne    0xffffff16
   6:	90                   	nop
   7:	0f 0b                	ud2
   9:	90                   	nop
   a:	e9 07 ff ff ff       	jmp    0xffffff16
   f:	66 0f 1f 44 00 00    	nopw   0x0(%rax,%rax,1)
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	90                   	nop
  1f:	90                   	nop
  20:	90                   	nop
  21:	90                   	nop
  22:	90                   	nop
  23:	90                   	nop
  24:	90                   	nop
  25:	f3 0f 1e fa          	endbr64
* 29:	83 f9 03             	cmp    $0x3,%ecx <-- trapping instruction
  2c:	0f 87 96 03 00 00    	ja     0x3c8
  32:	41 57                	push   %r15
  34:	41 56                	push   %r14
  36:	49 89 fe             	mov    %rdi,%r14
  39:	41 55                	push   %r13
  3b:	41 54                	push   %r12
  3d:	41                   	rex.B
  3e:	89                   	.byte 0x89