syzbot


BUG: unable to handle kernel paging request in udf_statfs

Status: upstream: reported on 2026/03/08 07:04
Reported-by: syzbot+464f8ed46b24690edf39@syzkaller.appspotmail.com
First crash: 8d17h, last: 8d17h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: use-after-free Read in udf_statfs 19 2 80d 84d 0/2 upstream: reported on 2025/12/22 06:27
upstream UBSAN: array-index-out-of-bounds in udf_statfs udf 15 C error error 3 1695d 1781d 20/29 fixed on 2021/11/10 00:50

Sample crash report:
BUG: unable to handle page fault for address: ffffed101829d363
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 23ffef067 P4D 23ffef067 PUD 13fff6067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 28911 Comm: syz.2.2908 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:udf_statfs+0xb87/0x1040 fs/udf/super.c:2444
Code: 08 48 89 df e8 1a f0 f4 fe 4c 89 74 24 18 4c 89 33 4d 85 ff 74 72 e8 28 e4 af fe 49 8d 7f 20 4d 8d 77 23 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 80 02 00 00 4c 89 f0 48 c1 e8 03 42 0f
RSP: 0018:ffffc90003c7f820 EFLAGS: 00010a06
RAX: 1ffff1101829d363 RBX: ffffc90003c7fa60 RCX: 0000000000080000
RDX: ffffc90017001000 RSI: 000000000000da10 RDI: ffff8880c14e9b18
RBP: ffffc90003c7f9a8 R08: ffff888067c43b80 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffffc90003c7fa40 R14: ffff8880c14e9b1b R15: ffff8880c14e9af8
FS:  00007f91c4ec36c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed101829d363 CR3: 0000000019de0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000000000b2
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 statfs_by_dentry fs/statfs.c:66 [inline]
 vfs_statfs+0x13d/0x2c0 fs/statfs.c:90
 ovl_check_namelen fs/overlayfs/super.c:922 [inline]
 ovl_get_upper+0x1c0/0x600 fs/overlayfs/super.c:1214
 ovl_fill_super+0x160c/0x2a30 fs/overlayfs/super.c:2068
 mount_nodev+0x52/0xe0 fs/super.c:1446
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f91c6c8a799
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:00007f91c4ec3028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f91c6f04090 RCX: 00007f91c6c8a799
RDX: 0000200000000b80 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007f91c6d20bd9 R08: 0000200000000200 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f91c6f04128 R14: 00007f91c6f04090 R15: 00007ffcc5fb6ab8
 </TASK>
Modules linked in:
CR2: ffffed101829d363
---[ end trace bfae8e8da3c6f01e ]---
RIP: 0010:udf_statfs+0xb87/0x1040 fs/udf/super.c:2444
Code: 08 48 89 df e8 1a f0 f4 fe 4c 89 74 24 18 4c 89 33 4d 85 ff 74 72 e8 28 e4 af fe 49 8d 7f 20 4d 8d 77 23 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 80 02 00 00 4c 89 f0 48 c1 e8 03 42 0f
RSP: 0018:ffffc90003c7f820 EFLAGS: 00010a06
RAX: 1ffff1101829d363 RBX: ffffc90003c7fa60 RCX: 0000000000080000
RDX: ffffc90017001000 RSI: 000000000000da10 RDI: ffff8880c14e9b18
RBP: ffffc90003c7f9a8 R08: ffff888067c43b80 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffffc90003c7fa40 R14: ffff8880c14e9b1b R15: ffff8880c14e9af8
FS:  00007f91c4ec36c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed101829d363 CR3: 0000000019de0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000000000b2
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	08 48 89             	or     %cl,-0x77(%rax)
   3:	df e8                	fucomip %st(0),%st
   5:	1a f0                	sbb    %al,%dh
   7:	f4                   	hlt
   8:	fe 4c 89 74          	decb   0x74(%rcx,%rcx,4)
   c:	24 18                	and    $0x18,%al
   e:	4c 89 33             	mov    %r14,(%rbx)
  11:	4d 85 ff             	test   %r15,%r15
  14:	74 72                	je     0x88
  16:	e8 28 e4 af fe       	call   0xfeafe443
  1b:	49 8d 7f 20          	lea    0x20(%r15),%rdi
  1f:	4d 8d 77 23          	lea    0x23(%r15),%r14
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 80 02 00 00    	jne    0x2b7
  37:	4c 89 f0             	mov    %r14,%rax
  3a:	48 c1 e8 03          	shr    $0x3,%rax
  3e:	42                   	rex.X
  3f:	0f                   	.byte 0xf

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/08 07:03 linux-5.15.y 91d48252ad4b 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan BUG: unable to handle kernel paging request in udf_statfs
* Struck through repros no longer work on HEAD.