syzbot


general protection fault in current_umask

Status: premoderation: reported on 2025/07/18 20:19
Reported-by: syzbot+d34d2ea786e6c433f472@syzkaller.appspotmail.com
First crash: 41d, last: 8d10h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 general protection fault in current_umask 2 C unreliable 5 135d 346d 0/2 auto-obsoleted due to no activity on 2025/07/24 17:05

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 UID: 0 PID: 1856 Comm: syz.2.520 Not tainted syzkaller #0 40a6597ee361193aa500bbffa95ee137cbfef8e8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:current_umask+0x4e/0x80 fs/fs_struct.c:158
Code: 81 c3 78 08 00 00 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 60 ca e5 ff 48 8b 1b 48 83 c3 0c 48 89 d8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 0c 8b 03 5b 41 5e 5d e9 8e cc 97 03 cc 89
RSP: 0018:ffffc9000de2f5e0 EFLAGS: 00010203
RAX: 0000000000000001 RBX: 000000000000000c RCX: ffff88810b385f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000de2f5f0 R08: 000000003e0539ff R09: 00000001effbffac
R10: effbffac00000000 R11: 0000000000000001 R12: ffff888123cdd040
R13: ffff888123cdd068 R14: dffffc0000000000 R15: ffff88811308b880
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f83ecc02bd0 CR3: 00000000072a8000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 mode_strip_umask include/linux/namei.h:111 [inline]
 vfs_prepare_mode fs/namei.c:3250 [inline]
 vfs_mknod+0x486/0x6d0 fs/namei.c:4126
 vfs_whiteout include/linux/fs.h:1970 [inline]
 ovl_do_whiteout fs/overlayfs/overlayfs.h:382 [inline]
 ovl_whiteout fs/overlayfs/dir.c:78 [inline]
 ovl_cleanup_and_whiteout+0x230/0x6a0 fs/overlayfs/dir.c:118
 ovl_remove_and_whiteout fs/overlayfs/dir.c:791 [inline]
 ovl_do_remove+0x886/0xcf0 fs/overlayfs/dir.c:914
 ovl_rmdir+0x1e/0x30 fs/overlayfs/dir.c:945
 vfs_rmdir+0x3dd/0x560 fs/namei.c:4340
 incfs_kill_sb+0x109/0x230 fs/incfs/vfs.c:1968
 deactivate_locked_super+0xd5/0x2a0 fs/super.c:476
 deactivate_super+0xb8/0xe0 fs/super.c:509
 cleanup_mnt+0x3f1/0x480 fs/namespace.c:1370
 __cleanup_mnt+0x1d/0x40 fs/namespace.c:1377
 task_work_run+0x1e3/0x250 kernel/task_work.c:240
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x9bc/0x2630 kernel/exit.c:953
 do_group_exit+0x22a/0x300 kernel/exit.c:1095
 get_signal+0x139d/0x14f0 kernel/signal.c:2933
 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0053:0x68daea46cc5edccd
Code: Unable to access opcode bytes at 0x68daea46cc5edca3.
RSP: 002b:0000000000000000 EFLAGS: 00000202 ORIG_RAX: 3b493b81f3229b3a
RAX: 000000004d98db3a RBX: 00000000323b3a02 RCX: 00000000060d53a8
RDX: 00000000134f4448 RSI: 000000006b179c8d RDI: 000000001df9f004
RBP: 0000000051feb9e6 R08: 9e00aa80badf9ca3 R09: 262a8f46fc1abed3
R10: d108cbe03db740d8 R11: f0a971f7bb0d4045 R12: 6c14749917ebe22e
R13: f371a5dada18777f R14: d6f16f60921a6484 R15: 83b20c40cccad612
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:current_umask+0x4e/0x80 fs/fs_struct.c:158
Code: 81 c3 78 08 00 00 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 60 ca e5 ff 48 8b 1b 48 83 c3 0c 48 89 d8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 0c 8b 03 5b 41 5e 5d e9 8e cc 97 03 cc 89
RSP: 0018:ffffc9000de2f5e0 EFLAGS: 00010203
RAX: 0000000000000001 RBX: 000000000000000c RCX: ffff88810b385f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000de2f5f0 R08: 000000003e0539ff R09: 00000001effbffac
R10: effbffac00000000 R11: 0000000000000001 R12: ffff888123cdd040
R13: ffff888123cdd068 R14: dffffc0000000000 R15: ffff88811308b880
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd91045ff8 CR3: 00000000072a8000 CR4: 00000000003526b0
----------------
Code disassembly (best guess):
   0:	81 c3 78 08 00 00    	add    $0x878,%ebx
   6:	48 89 d8             	mov    %rbx,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 60 ca e5 ff       	call   0xffe5ca7c
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	48 83 c3 0c          	add    $0xc,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 30       	movzbl (%rax,%r14,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	75 0c                	jne    0x3f
  33:	8b 03                	mov    (%rbx),%eax
  35:	5b                   	pop    %rbx
  36:	41 5e                	pop    %r14
  38:	5d                   	pop    %rbp
  39:	e9 8e cc 97 03       	jmp    0x397cccc
  3e:	cc                   	int3
  3f:	89                   	.byte 0x89

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/21 02:00 android16-6.12 7b5740102144 0b9605c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust general protection fault in current_umask
2025/07/18 20:18 android16-6.12 2e58e85c038f 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust general protection fault in current_umask
* Struck through repros no longer work on HEAD.