VFS: Close: file count is zero (use-after-free) (2)

Status: upstream: reported syz repro on 2026/08/09 05:17
Subsystems: fs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+592c653b056459925299@syzkaller.appspotmail.com
First crash: 9d22h, last: 3h34m
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
2949a68b assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ VFS: Close: file count is zero (use-after-free) (2) 2026/08/01 00:09 2026/08/01 00:09 2026/08/01 01:03 7664cf44
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fs?] VFS: Close: file count is zero (use-after-free) (2) 0 (1) 2026/08/09 05:17
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream VFS: Close: file count is zero (use-after-free) squashfs 2 syz, C done 16 784d 797d 0/29 auto-obsoleted due to no activity on 2024/07/25 12:57

Sample crash report:
 slab filp start ffff888028e2dc00 pointer offset 0 size 352
VFS: Close: file count is 0 (f_op=snd_ctl_f_ops)
------------[ cut here ]------------
kernel BUG at fs/open.c:1464!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 2 UID: 0 PID: 5914 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:filp_flush.cold+0x30/0x39 fs/open.c:1464
Code: 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 75 13 48 8b 73 48 48 c7 c7 20 a7 e5 8b e8 f9 4f fd ff 90 <0f> 0b e8 11 07 56 01 eb e6 e8 ca 78 e5 00 65 48 8b 2d 5a 45 3e 13
RSP: 0018:ffffc900037e7828 EFLAGS: 00010286
RAX: 0000000000000030 RBX: ffff888028e2dc00 RCX: 0000000000000000
RDX: 0000000000000030 RSI: ffffffff81e8bfd9 RDI: fffff520006fcef6
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: e000000000000000
R13: bfffffffffffffff R14: ffff88802e9e2528 R15: 0000000000000000
FS:  00007f799a6e96c0(0000) GS:ffff8880d5fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7999670000 CR3: 0000000048439000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 filp_close+0x1c/0x30 fs/open.c:1484
 gaudio_close_snd_dev drivers/usb/gadget/function/u_uac1_legacy.c:263 [inline]
 gaudio_cleanup+0x59/0x100 drivers/usb/gadget/function/u_uac1_legacy.c:305
 f_audio_bind+0x56c/0x660 drivers/usb/gadget/function/f_uac1_legacy.c:792
 usb_add_function+0x219/0x890 drivers/usb/gadget/composite.c:333
 configfs_composite_bind+0xd83/0x1960 drivers/usb/gadget/configfs.c:1802
 gadget_bind_driver+0x28c/0xbf0 drivers/usb/gadget/udc/core.c:1662
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 usb_gadget_register_driver_owner+0x132/0x210 drivers/usb/gadget/udc/core.c:1752
 gadget_dev_desc_UDC_store+0x1b0/0x2e0 drivers/usb/gadget/configfs.c:300
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f799979e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f799a6e9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7999a25fa0 RCX: 00007f799979e0d9
RDX: 000000000000000c RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007f7999835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7999a26038 R14: 00007f7999a25fa0 R15: 00007ffe3d1aeca8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:filp_flush.cold+0x30/0x39 fs/open.c:1464
Code: 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 75 13 48 8b 73 48 48 c7 c7 20 a7 e5 8b e8 f9 4f fd ff 90 <0f> 0b e8 11 07 56 01 eb e6 e8 ca 78 e5 00 65 48 8b 2d 5a 45 3e 13
RSP: 0018:ffffc900037e7828 EFLAGS: 00010286
RAX: 0000000000000030 RBX: ffff888028e2dc00 RCX: 0000000000000000
RDX: 0000000000000030 RSI: ffffffff81e8bfd9 RDI: fffff520006fcef6
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: e000000000000000
R13: bfffffffffffffff R14: ffff88802e9e2528 R15: 0000000000000000
FS:  00007f799a6e96c0(0000) GS:ffff8880d5fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7999670000 CR3: 0000000048439000 CR4: 0000000000352ef0

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 05:16 upstream 06cf61899d64 5d63f80b .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream VFS: Close: file count is zero (use-after-free)
2026/08/07 15:41 upstream f9a2394a2348 e4ef95d6 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/07 06:16 upstream fcaeecb8b0cd c38879ea .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/06 21:58 upstream fcaeecb8b0cd cc56899a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/05 06:43 upstream 562bfb501c54 52aa2820 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/05 04:38 upstream 562bfb501c54 52aa2820 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/05 02:14 upstream 562bfb501c54 52aa2820 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/04 10:03 upstream 848acc8ffe1b 9451e17e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/08/03 04:03 upstream bd1dde877520 e611ffe1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/07/31 05:07 upstream e05b559f9cda aaffb173 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/07/30 17:15 upstream 11028ab62899 0a1bc234 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root VFS: Close: file count is zero (use-after-free)
2026/07/31 15:58 upstream 8ba098e6b6ff db462e94 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 VFS: Close: file count is zero (use-after-free)
2026/07/30 10:29 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux master fc46aed51f62 2377cd3d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm32 VFS: Close: file count is zero (use-after-free)
* Struck through repros no longer work on HEAD.