BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1e35b3067 P4D 1e35b3067 PUD 1e35b2067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 26455 Comm: io_wqe_worker-0 Not tainted 5.8.0-next-20200810-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc9001cfbf910 EFLAGS: 00010246
RAX: 1ffffffff109f307 RBX: dffffc0000000000 RCX: ffff8880a91ba848
RDX: 0000000000001044 RSI: 0000000020001400 RDI: ffff8880a7102ac0
RBP: 0000000020001400 R08: 0000000000000001 R09: ffff888026684b28
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9001cfbfa28
R13: ffffffff884f9820 R14: 0000000000001044 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001e40e3000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 loop_rw_iter.part.0+0x26e/0x450 fs/io_uring.c:2850
 loop_rw_iter fs/io_uring.c:2829 [inline]
 io_write+0x6a2/0x7a0 fs/io_uring.c:3190
 io_issue_sqe+0x1b0/0x6130 fs/io_uring.c:5530
 io_wq_submit_work+0x183/0x3d0 fs/io_uring.c:5775
 io_worker_handle_work+0xa45/0x13f0 fs/io-wq.c:527
 io_wqe_worker+0xbf0/0x10e0 fs/io-wq.c:569
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:
CR2: 0000000000000000
---[ end trace 03de225c5675682c ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffffc9001cfbf910 EFLAGS: 00010246
RAX: 1ffffffff109f307 RBX: dffffc0000000000 RCX: ffff8880a91ba848
RDX: 0000000000001044 RSI: 0000000020001400 RDI: ffff8880a7102ac0
RBP: 0000000020001400 R08: 0000000000000001 R09: ffff888026684b28
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9001cfbfa28
R13: ffffffff884f9820 R14: 0000000000001044 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001e40e3000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400