==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
BUG: KASAN: null-ptr-deref in trylock_buffer include/linux/buffer_head.h:399 [inline]
BUG: KASAN: null-ptr-deref in lock_buffer include/linux/buffer_head.h:405 [inline]
BUG: KASAN: null-ptr-deref in alloc_branch fs/sysv/itree.c:148 [inline]
BUG: KASAN: null-ptr-deref in get_block+0x3e6/0x1580 fs/sysv/itree.c:251
Write of size 8 at addr 0000000000000000 by task syz-executor.3/5289

CPU: 0 PID: 5289 Comm: syz-executor.3 Not tainted 6.4.0-rc7-syzkaller-00226-ga92b7d26c743 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 print_report mm/kasan/report.c:465 [inline]
 kasan_report+0xec/0x130 mm/kasan/report.c:572
 check_region_inline mm/kasan/generic.c:181 [inline]
 kasan_check_range+0x141/0x190 mm/kasan/generic.c:187
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 test_and_set_bit_lock include/asm-generic/bitops/instrumented-lock.h:57 [inline]
 trylock_buffer include/linux/buffer_head.h:399 [inline]
 lock_buffer include/linux/buffer_head.h:405 [inline]
 alloc_branch fs/sysv/itree.c:148 [inline]
 get_block+0x3e6/0x1580 fs/sysv/itree.c:251
 __block_write_begin_int+0x3bd/0x14b0 fs/buffer.c:2064
 __block_write_begin fs/buffer.c:2114 [inline]
 block_write_begin+0xb9/0x4d0 fs/buffer.c:2175
 sysv_write_begin+0x31/0xd0 fs/sysv/itree.c:485
 generic_perform_write+0x256/0x570 mm/filemap.c:3929
 __generic_file_write_iter+0x2ae/0x500 mm/filemap.c:4057
 generic_file_write_iter+0xe3/0x350 mm/filemap.c:4089
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x945/0xd50 fs/read_write.c:584
 ksys_write+0x12b/0x250 fs/read_write.c:637
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7fe5579
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:00000000f7fe05cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000080
RDX: 000000000000fdef RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 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                   	retq
  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