[syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

syzbot
2025-09-20T00:13:35Z

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>

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