linux-kernel - [syzbot] [gfs2?] UBSAN: shift-out-of-bounds in gfs2_fill

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Message-ID: <67f8d2b2.050a0220.355867.001c.GAE@google.com>
Date: Fri, 11 Apr 2025 01:28:34 -0700
From: syzbot <syzbot+b0018b7468b2af33b4d5@...kaller.appspotmail.com>
To: agruenba@...hat.com, gfs2@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [gfs2?] UBSAN: shift-out-of-bounds in gfs2_fill_super

Hello,

syzbot found the following issue on:

HEAD commit:    a4cda136f021 Add linux-next specific files for 20250404
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15dc523f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8a257c454bb1afb7
dashboard link: https://syzkaller.appspot.com/bug?extid=b0018b7468b2af33b4d5
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/59048bc9c206/disk-a4cda136.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ad2ba7306f20/vmlinux-a4cda136.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3bef7acbf10/bzImage-a4cda136.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0018b7468b2af33b4d5@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:1172:19
shift exponent 4294967287 is too large for 64-bit type 'unsigned long'
CPU: 1 UID: 0 PID: 6127 Comm: syz.0.42 Not tainted 6.14.0-next-20250404-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:492
 gfs2_fill_super+0x255e/0x27b0 fs/gfs2/ops_fstype.c:1172
 get_tree_bdev_flags+0x490/0x5c0 fs/super.c:1636
 gfs2_get_tree+0x54/0x220 fs/gfs2/ops_fstype.c:1330
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
 do_mount fs/namespace.c:4219 [inline]
 __do_sys_mount fs/namespace.c:4430 [inline]
 __se_sys_mount+0x38c/0x400 fs/namespace.c:4407
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb2fa18e90a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb2fafe2e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb2fafe2ef0 RCX: 00007fb2fa18e90a
RDX: 0000200000000400 RSI: 0000200000012500 RDI: 00007fb2fafe2eb0
RBP: 0000200000000400 R08: 00007fb2fafe2ef0 R09: 0000000000000102
R10: 0000000000000102 R11: 0000000000000246 R12: 0000200000012500
R13: 00007fb2fafe2eb0 R14: 00000000000125bb R15: 00002000000004c0
 </TASK>
---[ end trace ]---


---
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