[syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    846bd2225ec3 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=144b8d04580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=9eefe09bedd093f156c2
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=1724be42580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12fc2712580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c53d48022f8a/disk-846bd222.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483534e784c8/vmlinux-846bd222.xz
kernel image: https://storage.googleapis.com/syzbot-assets/721b36eec9b3/bzImage-846bd222.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9eefe09bedd093f156c2@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: fs/nsfs.c:493 at nsfs_fh_to_dentry+0xcc5/0xdc0 fs/nsfs.c:493, CPU#1: syz.0.17/6050
Modules linked in:
CPU: 1 UID: 0 PID: 6050 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:nsfs_fh_to_dentry+0xcc5/0xdc0 fs/nsfs.c:493
Code: 7c 24 60 e9 10 f8 ff ff e8 48 01 79 ff 90 0f 0b 90 e9 09 f6 ff ff e8 3a 01 79 ff 90 0f 0b 90 e9 81 f6 ff ff e8 2c 01 79 ff 90 <0f> 0b 90 e9 d0 f6 ff ff e8 1e 01 79 ff 45 31 ff e9 d9 f7 ff ff e8
RSP: 0018:ffffc90002f97a20 EFLAGS: 00010293
RAX: ffffffff824717f4 RBX: 00000000effffffd RCX: ffff888031990000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000effffffd
RBP: ffffc90002f97b10 R08: ffffffff8fe4db77 R09: 1ffffffff1fc9b6e
R10: dffffc0000000000 R11: fffffbfff1fc9b6f R12: 1ffff920005f2f4c
R13: ffff888028d74894 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000555569cd2500(0000) GS:ffff8881258a2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32363fff CR3: 0000000028a1e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 exportfs_decode_fh_raw+0x178/0x6e0 fs/exportfs/expfs.c:456
 do_handle_to_path+0xa4/0x1a0 fs/fhandle.c:276
 handle_to_path fs/fhandle.c:400 [inline]
 do_handle_open+0x6b4/0x8f0 fs/fhandle.c:415
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a5d78ec29
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:00007ffff390c9e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00007f1a5d9d5fa0 RCX: 00007f1a5d78ec29
RDX: 0000000000400040 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f1a5d811e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1a5d9d5fa0 R14: 00007f1a5d9d5fa0 R15: 0000000000000003
 </TASK>


---
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] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in nsfs_fh_to_dentry

------------[ cut here ]------------
WARNING: fs/nsfs.c:495 at nsfs_fh_to_dentry+0xc56/0xd60 fs/nsfs.c:495, CPU#0: syz.0.17/6508
Modules linked in:
CPU: 0 UID: 0 PID: 6508 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:nsfs_fh_to_dentry+0xc56/0xd60 fs/nsfs.c:495
Code: 5c 24 60 e9 28 f8 ff ff e8 b7 01 79 ff 90 0f 0b 90 e9 1d f6 ff ff e8 a9 01 79 ff 90 0f 0b 90 e9 96 f6 ff ff e8 9b 01 79 ff 90 <0f> 0b 90 e9 ea f6 ff ff e8 8d 01 79 ff 31 db 4c 8d 74 24 70 e9 ed
RSP: 0018:ffffc90003b3fa20 EFLAGS: 00010293
RAX: ffffffff82471785 RBX: 00000000effffffd RCX: ffff88807de45ac0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000effffffd
RBP: ffffc90003b3fb10 R08: ffffffff8fe4db77 R09: 1ffffffff1fc9b6e
R10: dffffc0000000000 R11: fffffbfff1fc9b6f R12: 1ffff92000767f4c
R13: ffff88802e1605d4 R14: ffffc90003b3fa90 R15: 0000000000000000
FS:  00007fccf554a6c0(0000) GS:ffff8881257a2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2cd63fff CR3: 00000000334e0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 exportfs_decode_fh_raw+0x178/0x6e0 fs/exportfs/expfs.c:456
 do_handle_to_path+0xa4/0x1a0 fs/fhandle.c:276
 handle_to_path fs/fhandle.c:400 [inline]
 do_handle_open+0x6b4/0x8f0 fs/fhandle.c:415
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fccf478ec29
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:00007fccf554a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00007fccf49d5fa0 RCX: 00007fccf478ec29
RDX: 0000000000400040 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007fccf4811e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fccf49d6038 R14: 00007fccf49d5fa0 R15: 00007ffd8bdc2758
 </TASK>


Tested on:

commit:         846bd222 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17f8dc7c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=9eefe09bedd093f156c2
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=147e4d04580000

Re: [syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in nsfs_fh_to_dentry

------------[ cut here ]------------
WARNING: fs/nsfs.c:502 at nsfs_fh_to_dentry+0xcde/0xe00 fs/nsfs.c:502, CPU#0: syz.0.17/6525
Modules linked in:
CPU: 0 UID: 0 PID: 6525 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:nsfs_fh_to_dentry+0xcde/0xe00 fs/nsfs.c:502
Code: 5c 24 60 e9 08 f8 ff ff e8 2f 01 79 ff 90 0f 0b 90 e9 72 f6 ff ff e8 21 01 79 ff 90 0f 0b 90 e9 da f6 ff ff e8 13 01 79 ff 90 <0f> 0b 90 e9 1a f7 ff ff e8 c5 88 46 09 e8 00 01 79 ff 31 db e9 cd
RSP: 0018:ffffc90003007a20 EFLAGS: 00010293
RAX: ffffffff8247180d RBX: 00000000effffffd RCX: ffff88801bba5ac0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000effffffd
RBP: ffffc90003007b10 R08: ffffffff8fe4db77 R09: 1ffffffff1fc9b6e
R10: dffffc0000000000 R11: fffffbfff1fc9b6f R12: dffffc0000000000
R13: ffff888027365694 R14: ffffffff8e3df738 R15: 0000000000000000
FS:  00007f46068b46c0(0000) GS:ffff8881257a2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30363fff CR3: 00000000706b4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 exportfs_decode_fh_raw+0x178/0x6e0 fs/exportfs/expfs.c:456
 do_handle_to_path+0xa4/0x1a0 fs/fhandle.c:276
 handle_to_path fs/fhandle.c:400 [inline]
 do_handle_open+0x6b4/0x8f0 fs/fhandle.c:415
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f460598ec29
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:00007f46068b4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00007f4605bd5fa0 RCX: 00007f460598ec29
RDX: 0000000000400040 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 00007f4605a11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4605bd6038 R14: 00007f4605bd5fa0 R15: 00007ffed9ea2cf8
 </TASK>


Tested on:

commit:         846bd222 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10ef70e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=9eefe09bedd093f156c2
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10e888e2580000

Re: [syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+9eefe09bedd093f156c2@syzkaller.appspotmail.com
Tested-by: syzbot+9eefe09bedd093f156c2@syzkaller.appspotmail.com

Tested on:

commit:         846bd222 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17d650e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=9eefe09bedd093f156c2
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15c650e2580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+9eefe09bedd093f156c2@syzkaller.appspotmail.com
Tested-by: syzbot+9eefe09bedd093f156c2@syzkaller.appspotmail.com

Tested on:

commit:         846bd222 Add linux-next specific files for 20250919
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=127fa712580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=135377594f35b576
dashboard link: https://syzkaller.appspot.com/bug?extid=9eefe09bedd093f156c2
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16ff1534580000

Note: testing is done by a robot and is best-effort only.