BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD a500b067 P4D a500b067 PUD 93336067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9510 Comm: syz-executor.2 Not tainted 5.7.0-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:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90004b177a8 EFLAGS: 00010246
RAX: ffffffff81fa49c6 RBX: ffff888214a8a050 RCX: ffff88809f69a500
RDX: 0000000000000000 RSI: 00000000000016bc RDI: ffff888097c0a000
RBP: ffff888097c0a000 R08: 0000000000000000 R09: 0000000000000008
R10: ffffed1015d070fc R11: 0000000000000000 R12: 0000000000000008
R13: 0000000000000000 R14: 00000000000016bc R15: 0000000000000002
FS:  00007f400fde3700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000093976000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __ext4_journal_start_sb+0x26/0x160 fs/ext4/ext4_jbd2.c:92
 __ext4_journal_start fs/ext4/ext4_jbd2.h:325 [inline]
 ext4_dirty_inode+0xaa/0x110 fs/ext4/inode.c:5820
 __mark_inode_dirty+0xb4/0x670 fs/fs-writeback.c:2257
 mark_inode_dirty_sync include/linux/fs.h:2207 [inline]
 dquot_free_space include/linux/quotaops.h:385 [inline]
 dquot_free_block include/linux/quotaops.h:395 [inline]
 ext4_mb_new_blocks+0xa6c/0x1210 fs/ext4/mballoc.c:4613
 ext4_ext_map_blocks+0x29c9/0x6db0 fs/ext4/extents.c:4218
 ext4_map_blocks+0x8d8/0x1b00 fs/ext4/inode.c:621
 ext4_alloc_file_blocks+0x368/0xb60 fs/ext4/extents.c:4406
 ext4_fallocate+0x646/0x2c30 fs/ext4/extents.c:4675
 vfs_fallocate+0x56e/0x840 fs/open.c:309
 file_ioctl fs/ioctl.c:512 [inline]
 do_vfs_ioctl+0x1684/0x1a00 fs/ioctl.c:750
 ksys_ioctl fs/ioctl.c:769 [inline]
 __do_sys_ioctl fs/ioctl.c:780 [inline]
 __se_sys_ioctl+0x81/0x160 fs/ioctl.c:778
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca59
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f400fde2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e5d60 RCX: 000000000045ca59
RDX: 0000000020000000 RSI: 0000000040305828 RDI: 0000000000000003
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000032e R14: 00000000004c5b5a R15: 00007f400fde36d4
Modules linked in:
CR2: 0000000000000000
---[ end trace 96011635d1cfb007 ]---
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90004b177a8 EFLAGS: 00010246
RAX: ffffffff81fa49c6 RBX: ffff888214a8a050 RCX: ffff88809f69a500
RDX: 0000000000000000 RSI: 00000000000016bc RDI: ffff888097c0a000
RBP: ffff888097c0a000 R08: 0000000000000000 R09: 0000000000000008
R10: ffffed1015d070fc R11: 0000000000000000 R12: 0000000000000008
R13: 0000000000000000 R14: 00000000000016bc R15: 0000000000000002
FS:  00007f400fde3700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000093976000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400