BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 1cacd2067 P4D 1cacd2067 PUD 1c838a067 PMD 0 
Oops: 0000 [#1] SMP KASAN
CPU: 1 PID: 4886 Comm: syz-executor.1 Not tainted 5.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x42/0x60 kernel/kcov.c:202
Code: 34 24 74 0e 80 e6 01 74 34 80 b8 d4 12 00 00 00 74 2b 8b 90 b0 12 00 00 83 fa 02 75 20 48 8b 88 b8 12 00 00 8b 80 b4 12 00 00 <48> 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 66 2e
RSP: 0018:ffff8881c82df5f0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffea0006a9fd00 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff8179d94c RDI: 0000000000000001
RBP: 0000000000000003 R08: ffff8881c56fb100 R09: fffff94000d53fa7
R10: fffff94000d53fa6 R11: ffffea0006a9fd37 R12: ffffea0006a9fd00
R13: 0000000000000001 R14: ffff8881a9942348 R15: ffffea0006a9fd28
FS:  00007fc5d4908700(0000) GS:ffff8881db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001ccd1e000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 drop_buffers+0x12c/0x390 fs/buffer.c:3271
 try_to_free_buffers+0x1ce/0x3d0 fs/buffer.c:3290
 ext4_releasepage+0x350/0x440 fs/ext4/inode.c:3296
 try_to_release_page+0x1b7/0x260 mm/filemap.c:3483
 block_invalidatepage+0x424/0x4a0 fs/buffer.c:1541
 do_invalidatepage mm/truncate.c:163 [inline]
 truncate_cleanup_page+0xf9/0x2d0 mm/truncate.c:185
 truncate_inode_pages_range+0x563/0x1260 mm/truncate.c:365
 ext4_punch_hole+0x40d/0x12f0 fs/ext4/inode.c:4012
 ext4_fallocate+0xcab/0x3cc0 fs/ext4/extents.c:4865
 vfs_fallocate+0x484/0xa10 fs/open.c:309
 ioctl_preallocate+0x18e/0x200 fs/ioctl.c:504
 file_ioctl fs/ioctl.c:547 [inline]
 do_vfs_ioctl+0xdea/0x12c0 fs/ioctl.c:742
 ksys_ioctl+0xa3/0x180 fs/ioctl.c:761
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
 do_syscall_64+0xb6/0x5a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc5d4907c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc5d49086d4 RCX: 000000000045c849
RDX: 000000000040003f RSI: 0000000040305829 RDI: 0000000000000006
RBP: 000000000076c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000032e R14: 00000000004c593b R15: 000000000076c04c
Modules linked in:
CR2: 0000000000000000
---[ end trace 7ff7e49097b04d78 ]---
RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x42/0x60 kernel/kcov.c:202
Code: 34 24 74 0e 80 e6 01 74 34 80 b8 d4 12 00 00 00 74 2b 8b 90 b0 12 00 00 83 fa 02 75 20 48 8b 88 b8 12 00 00 8b 80 b4 12 00 00 <48> 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 66 2e
RSP: 0018:ffff8881c82df5f0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffea0006a9fd00 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff8179d94c RDI: 0000000000000001
RBP: 0000000000000003 R08: ffff8881c56fb100 R09: fffff94000d53fa7
R10: fffff94000d53fa6 R11: ffffea0006a9fd37 R12: ffffea0006a9fd00
R13: 0000000000000001 R14: ffff8881a9942348 R15: ffffea0006a9fd28
FS:  00007fc5d4908700(0000) GS:ffff8881db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001ccd1e000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400