Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 0 UID: 0 PID: 5340 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:bfs_move_block fs/bfs/file.c:43 [inline]
RIP: 0010:bfs_move_blocks fs/bfs/file.c:57 [inline]
RIP: 0010:bfs_get_block+0x583/0xb50 fs/bfs/file.c:126
Code: 89 c5 49 8d 7e 20 48 89 f8 48 c1 e8 03 80 3c 18 00 49 89 df 74 05 e8 cc 99 85 ff 49 8b 6e 20 49 8d 5d 28 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 ae 99 85 ff 4c 89 f7 48 83 c7 28
RSP: 0018:ffffc90006b7e538 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000028 RCX: ffff88803657a540
RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff88801ccb8560
RBP: 0000000000000200 R08: ffffea000148a3b7 R09: 1ffffd4000291476
R10: dffffc0000000000 R11: fffff94000291477 R12: 000000000000002a
R13: 0000000000000000 R14: ffff88801ccb8540 R15: dffffc0000000000
FS:  00007fedda0ac6c0(0000) GS:ffff88808c848000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fedda0ab680 CR3: 00000000434f5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2123
 block_write_begin+0x8d/0x120 fs/buffer.c:2234
 bfs_write_begin+0x35/0xd0 fs/bfs/file.c:180
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4363
 generic_file_write_iter+0xae/0x330 mm/filemap.c:4506
 __kernel_write_iter+0x44a/0x8f0 fs/read_write.c:621
 __kernel_write+0x106/0x170 fs/read_write.c:641
 __dump_emit fs/coredump.c:1220 [inline]
 dump_emit+0x920/0xb00 fs/coredump.c:1258
 writenote+0x1c0/0x2f0 fs/binfmt_elf.c:1434
 write_note_info fs/binfmt_elf.c:1936 [inline]
 elf_core_dump+0x3169/0x3a90 fs/binfmt_elf.c:2096
 coredump_write+0x1290/0x1960 fs/coredump.c:1052
 do_coredump fs/coredump.c:1131 [inline]
 vfs_coredump+0x36ff/0x44b0 fs/coredump.c:1200
 get_signal+0x1094/0x12c0 kernel/signal.c:3023
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 ret_from_fork+0x593/0xb70 arch/x86/kernel/process.c:167
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bfs_move_block fs/bfs/file.c:43 [inline]
RIP: 0010:bfs_move_blocks fs/bfs/file.c:57 [inline]
RIP: 0010:bfs_get_block+0x583/0xb50 fs/bfs/file.c:126
Code: 89 c5 49 8d 7e 20 48 89 f8 48 c1 e8 03 80 3c 18 00 49 89 df 74 05 e8 cc 99 85 ff 49 8b 6e 20 49 8d 5d 28 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 ae 99 85 ff 4c 89 f7 48 83 c7 28
RSP: 0018:ffffc90006b7e538 EFLAGS: 00010206
RAX: 0000000000000005 RBX: 0000000000000028 RCX: ffff88803657a540
RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff88801ccb8560
RBP: 0000000000000200 R08: ffffea000148a3b7 R09: 1ffffd4000291476
R10: dffffc0000000000 R11: fffff94000291477 R12: 000000000000002a
R13: 0000000000000000 R14: ffff88801ccb8540 R15: dffffc0000000000
FS:  00007fedda0ac6c0(0000) GS:ffff88808c848000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe4c72aff8 CR3: 00000000434f5000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	89 c5                	mov    %eax,%ebp
   2:	49 8d 7e 20          	lea    0x20(%r14),%rdi
   6:	48 89 f8             	mov    %rdi,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  11:	49 89 df             	mov    %rbx,%r15
  14:	74 05                	je     0x1b
  16:	e8 cc 99 85 ff       	call   0xff8599e7
  1b:	49 8b 6e 20          	mov    0x20(%r14),%rbp
  1f:	49 8d 5d 28          	lea    0x28(%r13),%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 ae 99 85 ff       	call   0xff8599e7
  39:	4c 89 f7             	mov    %r14,%rdi
  3c:	48 83 c7 28          	add    $0x28,%rdi