Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 8093 Comm: syz.2.958 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:nfsd4_cancel_copy_by_sb+0x161/0x840
Code: 48 42 80 3c 31 00 74 0f 48 8b 7c 24 10 e8 67 32 4d ff 48 8b 44 24 10 48 8b 5c 24 18 48 c1 e3 04 48 03 18 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 40 32 4d ff 48 8b 03 48 39 d8 48
RSP: 0018:ffffc900037cf280 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1102d08180d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc900037cf200
RBP: ffffc900037cf370 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520006f9e40 R12: ffffc900037cf300
R13: 1ffff920006f9e98 R14: dffffc0000000000 R15: 1ffff920006f9e5c
FS:  00007fe9fc7076c0(0000) GS:ffff8882a8f79000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000100 CR3: 000000016b3c8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 nfsd_nl_unlock_filesystem_doit+0x248/0x370
 genl_family_rcv_msg_doit+0x233/0x340
 genl_rcv_msg+0x614/0x7a0
 netlink_rcv_skb+0x226/0x4a0
 genl_rcv+0x28/0x40
 netlink_unicast+0x7bb/0x940
 netlink_sendmsg+0x813/0xb40
 sock_sendmsg_nosec+0x13a/0x180
 ____sys_sendmsg+0x54e/0x850
 ___sys_sendmsg+0x2a5/0x360
 __x64_sys_sendmsg+0x1b1/0x290
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9fb79e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe9fc707028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe9fba25fa0 RCX: 00007fe9fb79e0d9
RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007fe9fb835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe9fba26038 R14: 00007fe9fba25fa0 R15: 00007ffd527b08f8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:nfsd4_cancel_copy_by_sb+0x161/0x840
Code: 48 42 80 3c 31 00 74 0f 48 8b 7c 24 10 e8 67 32 4d ff 48 8b 44 24 10 48 8b 5c 24 18 48 c1 e3 04 48 03 18 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 40 32 4d ff 48 8b 03 48 39 d8 48
RSP: 0018:ffffc900037cf280 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 1ffff1102d08180d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc900037cf200
RBP: ffffc900037cf370 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520006f9e40 R12: ffffc900037cf300
R13: 1ffff920006f9e98 R14: dffffc0000000000 R15: 1ffff920006f9e5c
FS:  00007fe9fc7076c0(0000) GS:ffff8882a8f79000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000100 CR3: 000000016b3c8000 CR4: 00000000000006f0
