[syzbot] [hfs?] kernel BUG in may_open (3)

[syzbot] [hfs?] kernel BUG in may_open (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b6151c4e60e5 Merge tag 'erofs-for-6.19-rc5-fixes' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15d45922580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7b058fb1d7dbe6b1
dashboard link: https://syzkaller.appspot.com/bug?extid=f98189ed18c1f5f32e00
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a7d19a580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16a2f19a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6eb5179ada01/disk-b6151c4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bc48d1a68ed0/vmlinux-b6151c4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/061d4fb696a7/bzImage-b6151c4e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/df739de73585/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f98189ed18c1f5f32e00@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 1024
VFS_BUG_ON_INODE(!IS_ANON_FILE(inode)) encountered for inode ffff8880384b01e0
fs hfsplus mode 0 opflags 0x4 flags 0x0 state 0x70 count 2
------------[ cut here ]------------
kernel BUG at fs/namei.c:4210!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6062 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:may_open+0x4b1/0x4c0 fs/namei.c:4210
Code: 38 c1 0f 8c 1e fd ff ff 4c 89 e7 e8 c9 ec ef ff e9 11 fd ff ff e8 df b3 8d ff 4c 89 f7 48 c7 c6 80 53 f9 8a e8 10 eb f5 fe 90 <0f> 0b 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffc90003ba78e0 EFLAGS: 00010282
RAX: 0000000000000088 RBX: dffffc0000000000 RCX: b41eda36b1e3ff00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000008241 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000774ec1 R12: 0000000000000000
R13: ffffffff8d709d80 R14: ffff8880384b01e0 R15: 0000000000000002
FS:  000055557d7cd500(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f01916a5890 CR3: 0000000040598000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_open fs/namei.c:4635 [inline]
 path_openat+0x32a8/0x3df0 fs/namei.c:4796
 do_filp_open+0x1fa/0x410 fs/namei.c:4823
 do_sys_openat2+0x121/0x200 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_creat fs/open.c:1514 [inline]
 __se_sys_creat fs/open.c:1508 [inline]
 __x64_sys_creat+0x8f/0xc0 fs/open.c:1508
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f739c0cf749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd4aa21ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f739c325fa0 RCX: 00007f739c0cf749
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000200000000140
RBP: 00007f739c153f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f739c325fa0 R14: 00007f739c325fa0 R15: 0000000000000002
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:may_open+0x4b1/0x4c0 fs/namei.c:4210
Code: 38 c1 0f 8c 1e fd ff ff 4c 89 e7 e8 c9 ec ef ff e9 11 fd ff ff e8 df b3 8d ff 4c 89 f7 48 c7 c6 80 53 f9 8a e8 10 eb f5 fe 90 <0f> 0b 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90
RSP: 0018:ffffc90003ba78e0 EFLAGS: 00010282
RAX: 0000000000000088 RBX: dffffc0000000000 RCX: b41eda36b1e3ff00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000008241 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000774ec1 R12: 0000000000000000
R13: ffffffff8d709d80 R14: ffff8880384b01e0 R15: 0000000000000002
FS:  000055557d7cd500(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f01916a5890 CR3: 0000000040598000 CR4: 00000000003526f0


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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#syz undup

Re: [syzbot] [hfs?] kernel BUG in may_open (3)

[Christian Brauner]

On Mon, Jan 12, 2026 at 12:51:33AM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    b6151c4e60e5 Merge tag 'erofs-for-6.19-rc5-fixes' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15d45922580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=7b058fb1d7dbe6b1
> dashboard link: https://syzkaller.appspot.com/bug?extid=f98189ed18c1f5f32e00
> compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a7d19a580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16a2f19a580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/6eb5179ada01/disk-b6151c4e.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/bc48d1a68ed0/vmlinux-b6151c4e.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/061d4fb696a7/bzImage-b6151c4e.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/df739de73585/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f98189ed18c1f5f32e00@syzkaller.appspotmail.com
> 
> loop0: detected capacity change from 0 to 1024
> VFS_BUG_ON_INODE(!IS_ANON_FILE(inode)) encountered for inode ffff8880384b01e0
> fs hfsplus mode 0 opflags 0x4 flags 0x0 state 0x70 count 2

This is hfsplus adding inodes with a non-valid mode.

Re: [syzbot] [hfs?] kernel BUG in may_open (3)

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
The next patch would create the file fs/hfsplus/inode.c,
which already exists!  Applying it anyway.
checking file fs/hfsplus/inode.c
patch: **** unexpected end of file in patch



Tested on:

commit:         0f61b186 Linux 6.19-rc5
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=7b058fb1d7dbe6b1
dashboard link: https://syzkaller.appspot.com/bug?extid=f98189ed18c1f5f32e00
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1072a844580000

Re: [syzbot] [hfs?] kernel BUG in may_open (3)

[Dmitry Vyukov]

On Mon, 12 Jan 2026 at 10:27, 'Christian Brauner' via syzkaller-bugs
<syzkaller-bugs@googlegroups.com> wrote:
>
> On Mon, Jan 12, 2026 at 12:51:33AM -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    b6151c4e60e5 Merge tag 'erofs-for-6.19-rc5-fixes' of git:/..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15d45922580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=7b058fb1d7dbe6b1
> > dashboard link: https://syzkaller.appspot.com/bug?extid=f98189ed18c1f5f32e00
> > compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a7d19a580000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16a2f19a580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/6eb5179ada01/disk-b6151c4e.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/bc48d1a68ed0/vmlinux-b6151c4e.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/061d4fb696a7/bzImage-b6151c4e.xz
> > mounted in repro: https://storage.googleapis.com/syzbot-assets/df739de73585/mount_0.gz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+f98189ed18c1f5f32e00@syzkaller.appspotmail.com
> >
> > loop0: detected capacity change from 0 to 1024
> > VFS_BUG_ON_INODE(!IS_ANON_FILE(inode)) encountered for inode ffff8880384b01e0
> > fs hfsplus mode 0 opflags 0x4 flags 0x0 state 0x70 count 2
>
> This is hfsplus adding inodes with a non-valid mode.

+hfsplus maintainers

#syz set subsystems: hfs