WARNING in file_remove_privs_flags

Status: moderation: reported on 2026/05/12 16:39
Subsystems: fs
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+bc273027d5643e48e5b3@syzkaller.appspotmail.com
First crash: 93d, last: 18d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
5577bda1 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in file_remove_privs_flags 2026/05/17 18:13 2026/05/17 18:13 2026/05/17 19:07 de5aae85
Discussions (6)
Title Replies (including bot) Last reply
[PATCH v5] loop: Fix NULL pointer dereference in lo_rw_aio() 1 (1) 2026/07/16 00:05
[PATCH v4] loop: Fix NULL pointer dereference in lo_rw_aio() 1 (1) 2026/06/07 10:54
Re: [PATCH v3] loop: Fix NULL pointer dereference in lo_rw_aio() 8 (8) 2026/05/30 23:57
[PATCH v3] loop: Fix NULL pointer dereference in lo_rw_aio() 1 (1) 2026/05/25 03:40
[PATCH] loop: add sync_blockdev() in __loop_clr_fd() to prevent UAF 7 (7) 2026/05/22 11:50
[PATCH v2] loop: Fix NULL pointer dereference by synchronizing lo_release and loop_queue_rq 1 (1) 2026/05/15 01:38

Sample crash report:
------------[ cut here ]------------
d_inode(dentry) != file_inode(file)
WARNING: ./include/linux/fs.h:1363 at file_dentry include/linux/fs.h:1363 [inline], CPU#1: kworker/u8:0/12
WARNING: ./include/linux/fs.h:1363 at file_remove_privs_flags+0x556/0x610 fs/inode.c:2378, CPU#1: kworker/u8:0/12
Modules linked in:
CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Workqueue: loop4 loop_workfn
RIP: 0010:file_dentry include/linux/fs.h:1363 [inline]
RIP: 0010:file_remove_privs_flags+0x556/0x610 fs/inode.c:2378
Code: 00 75 4d 44 89 e8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 db 47 01 09 cc e8 85 11 80 ff e9 a5 fe ff ff e8 7b 11 80 ff 90 <0f> 0b 90 e9 b0 fb ff ff 44 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c d9
RSP: 0018:ffffc900001174a0 EFLAGS: 00010293
RAX: ffffffff82452715 RBX: ffff888033e792a0 RCX: ffff88801ca88000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900001175f8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5f1bf R12: 0000000000000000
R13: 1ffff110067cf254 R14: 1ffff1100be2bfb4 R15: 1ffff92000022ea0
FS:  0000000000000000(0000) GS:ffff888125d45000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555559143a68 CR3: 0000000036e1e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 shmem_file_write_iter+0xaa/0x120 mm/shmem.c:3408
 lo_rw_aio+0xc78/0xf30 include/linux/percpu-rwsem.h:-1
 do_req_filebacked drivers/block/loop.c:429 [inline]
 loop_handle_cmd drivers/block/loop.c:1917 [inline]
 loop_process_work+0x638/0x11d0 drivers/block/loop.c:1952
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/22 12:26 upstream 248951ddc14d 4a865b71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/07/13 15:26 upstream a13c140cc289 cc4833d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/07/12 06:35 upstream 44696aa3a489 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/07/10 14:06 upstream a635d6748234 99e64375 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/07/03 23:35 upstream 71dfdfb0209b fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/07/03 09:50 upstream 51512e22efe8 58bf2096 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/05/08 16:34 upstream 917719c412c4 b2988c17 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in file_remove_privs_flags
2026/06/28 06:39 linux-next 3d5670d672ae fb92f11c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in file_remove_privs_flags
2026/05/13 20:54 linux-next e98d21c170b0 fec2a7ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in file_remove_privs_flags
* Struck through repros no longer work on HEAD.