------------[ cut here ]------------
WARNING: CPU: 0 PID: 32458 at fs/read_write.c:504 __kernel_write_iter+0x5b4/0x7b0 fs/read_write.c:504
Modules linked in:
CPU: 0 PID: 32458 Comm: syz-executor.1 Not tainted 6.6.0-syzkaller-12401-g8f6f76a6a29f #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__kernel_write_iter+0x5b4/0x7b0 fs/read_write.c:504
Code: c7 a0 ae 17 8d e8 5c 94 82 08 31 ff 89 c5 89 c6 e8 f1 43 9a ff 85 ed 75 1f 48 c7 c5 ea ff ff ff e9 0b ff ff ff e8 6c 48 9a ff <0f> 0b 48 c7 c5 f7 ff ff ff e9 f8 fe ff ff e8 59 48 9a ff 48 b8 00
RSP: 0018:ffffc9002ae97678 EFLAGS: 00010287
RAX: 000000000000a255 RBX: ffff888077075e00 RCX: ffffc9000c0a1000
RDX: 0000000000040000 RSI: ffffffff81ee6274 RDI: 0000000000000005
RBP: 00000000000a001d R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880762dd808
R13: 1ffff920055d2ed1 R14: 0000000000000000 R15: ffff888077075e50
FS:  0000000000000000(0000) GS:ffff88802c600000(0063) knlGS:00000000f7f0eb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000056972480 CR3: 0000000026e4d000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __kernel_write fs/read_write.c:537 [inline]
 kernel_write fs/read_write.c:558 [inline]
 kernel_write+0x1f8/0x6c0 fs/read_write.c:548
 write_buf fs/btrfs/send.c:648 [inline]
 send_header fs/btrfs/send.c:766 [inline]
 send_subvol fs/btrfs/send.c:7936 [inline]
 btrfs_ioctl_send+0x2313/0x6b70 fs/btrfs/send.c:8312
 _btrfs_ioctl_send+0x117/0x2f0 fs/btrfs/ioctl.c:4369
 btrfs_ioctl+0x3881/0x5d90 fs/btrfs/ioctl.c:4660
 __do_compat_sys_ioctl+0x2bf/0x330 fs/ioctl.c:972
 do_syscall_32_irqs_on arch/x86/entry/common.c:164 [inline]
 __do_fast_syscall_32+0x61/0xe0 arch/x86/entry/common.c:230
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:255
 entry_SYSENTER_compat_after_hwframe+0x70/0x7a
RIP: 0023:0xf7f34579
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:00000000f7f0e5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000040489426
RDX: 0000000020000140 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
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