linux-kernel - Re: [syzbot] [nfs?] WARNING in nsfs_fh_to

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Message-ID: <68ce6775.050a0220.139b6.0011.GAE@google.com>
Date: Sat, 20 Sep 2025 01:36:05 -0700
From: syzbot <syzbot+9eefe09bedd093f156c2@...kaller.appspotmail.com>
To: kartikey406@...il.com, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [nfs?] WARNING in nsfs_fh_to_dentry

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