[moderation] [fs?] kernel BUG in vxfs_read_olt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: df685633c3db Merge tag 'rcu-fixes.v7.1-20260519a' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15312d96580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7f195f6be48c12ec
dashboard link: https://syzkaller.appspot.com/bug?extid=7d0de452405deea7c9b1
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [h...@infradead.org linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-df685633.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d8ce459af2e/vmlinux-df685633.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5f8a4c255465/bzImage-df685633.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7d0de4...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 128
------------[ cut here ]------------
kernel BUG at fs/freevxfs/vxfs_olt.c:35!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5323 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:vxfs_oblock fs/freevxfs/vxfs_olt.c:35 [inline]
RIP: 0010:vxfs_read_olt+0x670/0x680 fs/freevxfs/vxfs_olt.c:60
Code: 0f 8c b1 fb ff ff e8 ef 64 7c ff 48 8b 14 24 e9 a3 fb ff ff e8 11 99 0f ff 90 0f 0b e8 09 99 0f ff 90 0f 0b e8 01 99 0f ff 90 <0f> 0b cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90
RSP: 0018:ffffc9000e037ae8 EFLAGS: 00010283
RAX: ffffffff82b63b2f RBX: 0000000000000200 RCX: 0000000000100000
RDX: ffffc9000efa2000 RSI: 0000000000001a89 RDI: 0000000000001a8a
RBP: ffff8880393c6018 R08: ffff88801cc25807 R09: 1ffff11003984b00
R10: dffffc0000000000 R11: ffffed1003984b01 R12: 0000000000000000
R13: 0000000000000200 R14: dffffc0000000000 R15: ffff8880393c6000
FS: 00007f38aa7f56c0(0000) GS:ffff88808c87e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa1e0261000 CR3: 0000000012fc4000 CR4: 0000000000352ef0
Call Trace:
<TASK>
vxfs_fill_super+0x4c8/0x830 fs/freevxfs/vxfs_super.c:251
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3758 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3834
do_mount fs/namespace.c:4167 [inline]
__do_sys_mount fs/namespace.c:4383 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4360
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f38ae39e0ca
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f38aa7f4e18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f38aa7f4ea0 RCX: 00007f38ae39e0ca
RDX: 0000200000009e00 RSI: 0000200000000100 RDI: 00007f38aa7f4e60
RBP: 0000200000009e00 R08: 00007f38aa7f4ea0 R09: 0000000002008814
R10: 0000000002008814 R11: 0000000000000246 R12: 0000200000000100
R13: 00007f38aa7f4e60 R14: 0000000000009e0b R15: 00002000000000c0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vxfs_oblock fs/freevxfs/vxfs_olt.c:35 [inline]
RIP: 0010:vxfs_read_olt+0x670/0x680 fs/freevxfs/vxfs_olt.c:60
Code: 0f 8c b1 fb ff ff e8 ef 64 7c ff 48 8b 14 24 e9 a3 fb ff ff e8 11 99 0f ff 90 0f 0b e8 09 99 0f ff 90 0f 0b e8 01 99 0f ff 90 <0f> 0b cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90
RSP: 0018:ffffc9000e037ae8 EFLAGS: 00010283
RAX: ffffffff82b63b2f RBX: 0000000000000200 RCX: 0000000000100000
RDX: ffffc9000efa2000 RSI: 0000000000001a89 RDI: 0000000000001a8a
RBP: ffff8880393c6018 R08: ffff88801cc25807 R09: 1ffff11003984b00
R10: dffffc0000000000 R11: ffffed1003984b01 R12: 0000000000000000
R13: 0000000000000200 R14: dffffc0000000000 R15: ffff8880393c6000
FS: 00007f38aa7f56c0(0000) GS:ffff88808c87e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa1e0261000 CR3: 0000000012fc4000 CR4: 0000000000352ef0


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