loop0: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/bcachefs/super-io.c:652:18
shift exponent 255 is too large for 32-bit type 'int'
CPU: 2 PID: 6486 Comm: syz-executor.0 Not tainted 6.9.0-rc7-syzkaller-00023-g6d7ddd805123 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:114
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x2a5/0x480 lib/ubsan.c:468
 read_one_super.cold+0x38/0x61 fs/bcachefs/super-io.c:652
 __bch2_read_super+0x4d6/0x12a0 fs/bcachefs/super-io.c:750
 bch2_fs_open+0x3e5/0x10f0 fs/bcachefs/super.c:2049
 bch2_mount+0xd41/0x1090 fs/bcachefs/fs.c:1903
 legacy_get_tree+0x109/0x220 fs/fs_context.c:662
 vfs_get_tree+0x8f/0x380 fs/super.c:1779
 do_new_mount fs/namespace.c:3352 [inline]
 path_mount+0x6e1/0x1f10 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount fs/namespace.c:3875 [inline]
 __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf72a5579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5e97400 EFLAGS: 00000292 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00000000f5e97460 RCX: 0000000020000000
RDX: 0000000020011a00 RSI: 0000000001200014 RDI: 00000000f5e974a0
RBP: 00000000f5e97460 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
---[ end trace ]---
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi