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

Status: moderation: reported on 2026/08/03 10:36
Subsystems: fs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+f95090e892d74b08ac6f@syzkaller.appspotmail.com
First crash: 6d16h, last: 20h20m
▶ ▼ ✨ 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
▶ ▼ 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 781d 794d 0/29 auto-obsoleted due to no activity on 2024/07/25 12:57

Sample crash report:
 slab filp start ffff888000223c40 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:1466!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5340 Comm: syz.0.0 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+0x184/0x190 fs/open.c:1464
Code: 48 83 c3 48 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 dc 13 ee ff 48 8b 33 48 c7 c7 80 8c fe 8b e8 4d 7e df fe 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000f1876b8 EFLAGS: 00010246
RAX: 0000000000000030 RBX: ffff888000223c88 RCX: 20c5662edc243700
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000f1877d8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1d3ca24 R12: dffffc0000000000
R13: ffff888012e5c528 R14: 0000000000000000 R15: 0000000000000003
FS:  00007f63d1fbc6c0(0000) GS:ffff88808c540000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ad1538e6b0 CR3: 00000000424da000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 filp_close+0x1d/0x40 fs/open.c:1484
 gaudio_close_snd_dev drivers/usb/gadget/function/u_uac1_legacy.c:263 [inline]
 gaudio_cleanup+0x54/0xf0 drivers/usb/gadget/function/u_uac1_legacy.c:305
 f_audio_bind+0x4a0/0x630 drivers/usb/gadget/function/f_uac1_legacy.c:792
 usb_add_function+0x2e1/0x9f0 drivers/usb/gadget/composite.c:333
 configfs_composite_bind+0xde0/0x1410 drivers/usb/gadget/configfs.c:1802
 gadget_bind_driver+0x2ca/0x9e0 drivers/usb/gadget/udc/core.c:1662
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
 __driver_attach+0x339/0x600 drivers/base/dd.c:1292
 bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383
 bus_add_driver+0x345/0x670 drivers/base/bus.c:763
 driver_register+0x23a/0x320 drivers/base/driver.c:174
 usb_gadget_register_driver_owner+0xf9/0x270 drivers/usb/gadget/udc/core.c:1752
 gadget_dev_desc_UDC_store+0x1c9/0x2f0 drivers/usb/gadget/configfs.c:300
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x337/0x430 fs/configfs/file.c:229
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f63d119e019
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:00007f63d1fbbfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f63d1426090 RCX: 00007f63d119e019
RDX: 000000000000000c RSI: 0000200000000400 RDI: 0000000000000007
RBP: 00007f63d123500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f63d1426128 R14: 00007f63d1426090 R15: 00007ffd1c6a5168
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:filp_flush+0x184/0x190 fs/open.c:1464
Code: 48 83 c3 48 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 dc 13 ee ff 48 8b 33 48 c7 c7 80 8c fe 8b e8 4d 7e df fe 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000f1876b8 EFLAGS: 00010246
RAX: 0000000000000030 RBX: ffff888000223c88 RCX: 20c5662edc243700
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000f1877d8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1d3ca24 R12: dffffc0000000000
R13: ffff888012e5c528 R14: 0000000000000000 R15: 0000000000000003
FS:  00007f63d1fbc6c0(0000) GS:ffff88808c540000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f94cfbbaf90 CR3: 00000000424da000 CR4: 0000000000352ef0

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.