syzbot


WARNING: refcount bug in p9_req_put (3)

Status: upstream: reported on 2024/01/26 09:05
Subsystems: v9fs
[Documentation on labels]
Reported-by: syzbot+d99d2414db66171fccbb@syzkaller.appspotmail.com
First crash: 88d, last: 4d04h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] [v9fs?] WARNING: refcount bug in p9_req_put (3) 2 (3) 2024/01/30 16:41
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 WARNING: refcount bug in p9_req_put 2 1631d 1672d 0/1 auto-closed as invalid on 2020/02/28 21:29
upstream WARNING: refcount bug in p9_req_put v9fs syz inconclusive done 6 1429d 1981d 15/26 fixed on 2020/11/16 12:12
upstream WARNING: refcount bug in p9_req_put (2) v9fs 9 232d 578d 0/26 auto-obsoleted due to no activity on 2023/12/09 05:29

Sample crash report:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 3 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 3 PID: 3 Comm: pool_workqueue_ Not tainted 6.9.0-rc3-syzkaller-00399-g72374d71c315 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 a8 74 0e fd 84 db 0f 85 66 ff ff ff e8 1b 7a 0e fd c6 05 aa 65 09 0b 01 90 48 c7 c7 a0 eb 6e 8b e8 97 e8 d0 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 f8 79 0e fd 0f b6 1d 85 65 09 0b 31
RSP: 0018:ffffc900008f8bf8 EFLAGS: 00010086
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81503349
RDX: ffff8880162ec880 RSI: ffffffff81503356 RDI: 0000000000000001
RBP: ffff888025610998 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: dffffc0000000000
R13: ffff888025610998 R14: ffff888047bff800 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88806b500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f66e9bc5c98 CR3: 0000000026640000 CR4: 0000000000350ef0
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+0x1f4/0x250 net/9p/client.c:401
 req_done+0x1e7/0x2f0 net/9p/trans_virtio.c:147
 vring_interrupt drivers/virtio/virtio_ring.c:2595 [inline]
 vring_interrupt+0x31b/0x400 drivers/virtio/virtio_ring.c:2570
 __handle_irq_event_percpu+0x229/0x7c0 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:161 [inline]
 handle_irq arch/x86/kernel/irq.c:238 [inline]
 __common_interrupt+0xde/0x250 arch/x86/kernel/irq.c:257
 common_interrupt+0x52/0xd0 arch/x86/kernel/irq.c:247
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:__do_softirq+0x1dc/0x922 kernel/softirq.c:540
Code: 89 44 24 18 44 88 74 24 3b 48 c7 c7 80 4f 0b 8b e8 59 4c fc ff 65 66 c7 05 27 75 25 75 00 00 e8 5a 7b b6 f6 fb bb ff ff ff ff <49> c7 c6 c0 a0 40 8d 41 0f bc dc 83 c3 01 0f 85 a7 00 00 00 e9 b4
RSP: 0018:ffffc900008f8f30 EFLAGS: 00000202
RAX: 000000000000b268 RBX: 00000000ffffffff RCX: 1ffffffff1f3d849
RDX: 0000000000000000 RSI: ffffffff8b0cae00 RDI: ffffffff8b6f4e60
RBP: 00000000ffffd704 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8f9f04d7 R11: 0000000000000000 R12: 0000000000000282
R13: 000000000000000a R14: 0000000000000001 R15: 0000000000000000
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:633 [inline]
 irq_exit_rcu+0xb9/0x120 kernel/softirq.c:645
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1043
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lockdep_unregister_key+0x1ab/0x280 kernel/locking/lockdep.c:6476
Code: 21 dc 93 48 89 df e8 54 fd ff ff 48 89 df e8 5c d9 ff ff e8 57 db ff ff 9c 58 f6 c4 02 75 66 41 f7 c5 00 02 00 00 74 01 fb 5b <5d> 41 5c 41 5d 41 5e 41 5f e9 37 13 0a 00 48 c7 c0 98 38 9f 8f 48
RSP: 0018:ffffc90000067df8 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffff8880465490e8 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffffffff8b0cb0c0 RDI: ffffffff8b6f4e60
RBP: ffff888041cf7138 R08: ffffffff92a0be38 R09: 0000000000000ffc
R10: ffffffff93dcbc4f R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000246 R14: ffffffff93f67958 R15: ffff888041cf7140
 wq_unregister_lockdep kernel/workqueue.c:4655 [inline]
 pwq_release_workfn+0x539/0x9d0 kernel/workqueue.c:4958
 kthread_worker_fn+0x305/0xb20 kernel/kthread.c:841
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
----------------
Code disassembly (best guess):
   0:	89 44 24 18          	mov    %eax,0x18(%rsp)
   4:	44 88 74 24 3b       	mov    %r14b,0x3b(%rsp)
   9:	48 c7 c7 80 4f 0b 8b 	mov    $0xffffffff8b0b4f80,%rdi
  10:	e8 59 4c fc ff       	call   0xfffc4c6e
  15:	65 66 c7 05 27 75 25 	movw   $0x0,%gs:0x75257527(%rip)        # 0x75257546
  1c:	75 00 00
  1f:	e8 5a 7b b6 f6       	call   0xf6b67b7e
  24:	fb                   	sti
  25:	bb ff ff ff ff       	mov    $0xffffffff,%ebx
* 2a:	49 c7 c6 c0 a0 40 8d 	mov    $0xffffffff8d40a0c0,%r14 <-- trapping instruction
  31:	41 0f bc dc          	bsf    %r12d,%ebx
  35:	83 c3 01             	add    $0x1,%ebx
  38:	0f 85 a7 00 00 00    	jne    0xe5
  3e:	e9                   	.byte 0xe9
  3f:	b4                   	.byte 0xb4

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/15 09:24 upstream 72374d71c315 c8349e48 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: refcount bug in p9_req_put
2024/04/15 09:24 upstream 72374d71c315 c8349e48 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: refcount bug in p9_req_put
2024/03/02 16:41 upstream 5ad3cb0ed525 25905f5d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: refcount bug in p9_req_put
2024/01/27 14:27 upstream 3a5879d495b2 cc4a4020 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: refcount bug in p9_req_put
2024/01/21 21:11 upstream 4fbbed787267 9bd8dcda .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: refcount bug in p9_req_put
* Struck through repros no longer work on HEAD.