------------[ cut here ]------------
n > v || v > page_size(head)
WARNING: lib/iov_iter.c:356 at page_copy_sane lib/iov_iter.c:356 [inline], CPU#3: syz.9.4360/21383
WARNING: lib/iov_iter.c:356 at page_copy_sane lib/iov_iter.c:338 [inline], CPU#3: syz.9.4360/21383
WARNING: lib/iov_iter.c:356 at copy_page_to_iter+0xbd/0x370 lib/iov_iter.c:365, CPU#3: syz.9.4360/21383
Modules linked in:

CPU: 3 UID: 0 PID: 21383 Comm: syz.9.4360 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:page_copy_sane lib/iov_iter.c:356 [inline]
RIP: 0010:page_copy_sane lib/iov_iter.c:338 [inline]
RIP: 0010:copy_page_to_iter+0xbd/0x370 lib/iov_iter.c:365
Code: 83 e8 01 49 09 c6 4d 21 ee 4c 29 f3 48 c1 fb 06 48 c1 e3 0c 4c 01 fb 48 89 de e8 5e 75 11 fd 48 39 eb 73 27 e8 34 7b 11 fd 90 <0f> 0b 90 45 31 f6 e8 28 7b 11 fd 4c 89 f0 48 83 c4 10 5b 5d 41 5c
RSP: 0018:ffffc90006237730 EFLAGS: 00010293

RAX: 0000000000000000 RBX: 000000000000022e RCX: ffffffff84f71062
RDX: ffff88804f08a500 RSI: ffffffff84f7106c RDI: ffff88804f08a500
RBP: ffffffffffffff6c R08: 0000000000000006 R09: ffffffffffffff6c
R10: 000000000000022e R11: 0000000000000000 R12: 00000000000002c2
R13: ffffea00004b1540 R14: ffffea00004b1540 R15: 000000000000022e
FS:  00007f375e2456c0(0000) GS:ffff8880d6679000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ce0f913300 CR3: 000000002e256000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __sk_msg_recvmsg+0x4fd/0x10c0 net/core/skmsg.c:443
 udp_bpf_recvmsg net/ipv4/udp_bpf.c:83 [inline]
 udp_bpf_recvmsg+0x1a8/0x9d0 net/ipv4/udp_bpf.c:61
 inet_recvmsg+0x455/0x4c0 net/ipv4/af_inet.c:896
 sock_recvmsg_nosec net/socket.c:1137 [inline]
 sock_recvmsg+0x187/0x1f0 net/socket.c:1159
 ____sys_recvmsg+0x218/0x640 net/socket.c:2918
 ___sys_recvmsg+0x16a/0x1a0 net/socket.c:2960
 do_recvmmsg+0x301/0x760 net/socket.c:3055
 __sys_recvmmsg net/socket.c:3129 [inline]
 __do_sys_recvmmsg net/socket.c:3152 [inline]
 __se_sys_recvmmsg net/socket.c:3145 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3145
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f375d39cdd9
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:00007f375e245028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f375d616090 RCX: 00007f375d39cdd9
RDX: 0000000000000012 RSI: 0000200000000400 RDI: 0000000000000008
RBP: 00007f375d432d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000040000021 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f375d616128 R14: 00007f375d616090 R15: 00007ffe5a799f78
 </TASK>