linux-kernel - [syzbot] [overlayfs?] WARNING in ovl_copy_up

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Message-ID: <68d580e5.a00a0220.303701.0019.GAE@google.com>
Date: Thu, 25 Sep 2025 10:50:29 -0700
From: syzbot <syzbot+f754e01116421e9754b9@...kaller.appspotmail.com>
To: amir73il@...il.com, linux-kernel@...r.kernel.org, 
	linux-unionfs@...r.kernel.org, miklos@...redi.hu, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [overlayfs?] WARNING in ovl_copy_up_file (2)

Hello,

syzbot found the following issue on:

HEAD commit:    bf40f4b87761 Merge tag 'probes-fixes-v6.17-rc7' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1636e142580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bf99f2510ef92ba5
dashboard link: https://syzkaller.appspot.com/bug?extid=f754e01116421e9754b9
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=13eb34e2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10ca2f12580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-bf40f4b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2fe4635de41e/vmlinux-bf40f4b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/acfb085eaa3e/bzImage-bf40f4b8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1280fcf9f9a9/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f754e01116421e9754b9@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 8
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5501 at fs/overlayfs/copy_up.c:276 ovl_copy_up_file+0x640/0x6a0 fs/overlayfs/copy_up.c:276
Modules linked in:
CPU: 0 UID: 0 PID: 5501 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ovl_copy_up_file+0x640/0x6a0 fs/overlayfs/copy_up.c:276
Code: e9 2d ff ff ff e8 60 ac 8b fe 49 bc 00 00 00 00 00 fc ff df e9 14 ff ff ff e8 4c ac 8b fe 90 0f 0b 90 eb 09 e8 41 ac 8b fe 90 <0f> 0b 90 41 bd fb ff ff ff 48 8b 5c 24 10 e9 8d fb ff ff e8 d8 35
RSP: 0018:ffffc90002b0f040 EFLAGS: 00010293
RAX: ffffffff833410ff RBX: ffffc90002b0f0c0 RCX: ffff88801f022440
RDX: 0000000000000000 RSI: fc0000000000000a RDI: 0000000000000000
RBP: ffffc90002b0f170 R08: ffffc90002b0f0cf R09: 0000000000000000
R10: ffffc90002b0f0c0 R11: fffff52000561e1a R12: dffffc0000000000
R13: fc0000000000000a R14: ffff888033b7d380 R15: ffff888042c0f028
FS:  0000555584fee500(0000) GS:ffff88808d007000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2eacb909c0 CR3: 0000000059e0d000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ovl_copy_up_tmpfile fs/overlayfs/copy_up.c:885 [inline]
 ovl_do_copy_up fs/overlayfs/copy_up.c:999 [inline]
 ovl_copy_up_one fs/overlayfs/copy_up.c:1202 [inline]
 ovl_copy_up_flags+0x1502/0x2fe0 fs/overlayfs/copy_up.c:1257
 ovl_open+0x138/0x2f0 fs/overlayfs/file.c:211
 do_dentry_open+0x953/0x13f0 fs/open.c:965
 vfs_open+0x3b/0x340 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x2ee5/0x3830 fs/namei.c:4046
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1be718eec9
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:00007fff614ed578 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f1be73e5fa0 RCX: 00007f1be718eec9
RDX: 0000000000000042 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f1be7211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1be73e5fa0 R14: 00007f1be73e5fa0 R15: 0000000000000004
 </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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