==================================================================
BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
CPU: 1 PID: 11979 Comm: syz-executor4 Not tainted 5.0.0-rc1+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x173/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x12e/0x2a0 mm/kmsan/kmsan.c:600
 kmsan_internal_check_memory+0x465/0xb10 mm/kmsan/kmsan.c:663
 kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:601
 _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
 copy_to_user include/linux/uaccess.h:174 [inline]
 move_addr_to_user+0x311/0x570 net/socket.c:227
 ___sys_recvmsg+0xb65/0x1310 net/socket.c:2284
 __sys_recvmsg net/socket.c:2327 [inline]
 __do_sys_recvmsg net/socket.c:2337 [inline]
 __se_sys_recvmsg+0x2fa/0x450 net/socket.c:2334
 __x64_sys_recvmsg+0x4a/0x70 net/socket.c:2334
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457ec9
Code: 6d 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f5d5c87fc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457ec9
RDX: 0000000000002000 RSI: 0000000020000400 RDI: 0000000000000003
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5d5c8806d4
R13: 00000000004c4a60 R14: 00000000004d8140 R15: 00000000ffffffff

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
 kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
 __msan_chain_origin+0x70/0xe0 mm/kmsan/kmsan_instr.c:200
 ipv6_recv_error+0x1e3f/0x1eb0 net/ipv6/datagram.c:475
 udpv6_recvmsg+0x397/0x2520 net/ipv6/udp.c:296
 inet_recvmsg+0x4fb/0x600 net/ipv4/af_inet.c:830
 sock_recvmsg_nosec net/socket.c:794 [inline]
 sock_recvmsg+0x1d1/0x230 net/socket.c:801
 ___sys_recvmsg+0xa6f/0x1310 net/socket.c:2278
 __sys_recvmsg net/socket.c:2327 [inline]
 __do_sys_recvmsg net/socket.c:2337 [inline]
 __se_sys_recvmsg+0x2fa/0x450 net/socket.c:2334
 __x64_sys_recvmsg+0x4a/0x70 net/socket.c:2334
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
 kmsan_internal_poison_shadow+0x92/0x150 mm/kmsan/kmsan.c:159
 kmsan_kmalloc+0xa6/0x130 mm/kmsan/kmsan_hooks.c:176
 kmsan_slab_alloc+0xe/0x10 mm/kmsan/kmsan_hooks.c:185
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2754 [inline]
 __kmalloc_node_track_caller+0xe9e/0xff0 mm/slub.c:4377
 __kmalloc_reserve net/core/skbuff.c:140 [inline]
 __alloc_skb+0x309/0xa20 net/core/skbuff.c:208
IPVS: ftp: loaded support on port[0] = 21
 alloc_skb include/linux/skbuff.h:1012 [inline]
 ipv6_local_error+0x19f/0x9d0 net/ipv6/datagram.c:334
 __ip6_append_data+0x1092/0x5dc0 net/ipv6/ip6_output.c:1321
 ip6_make_skb+0x6cc/0xcf0 net/ipv6/ip6_output.c:1806
 udpv6_sendmsg+0x3f8e/0x45d0 net/ipv6/udp.c:1460
 inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 __sys_sendto+0x8c4/0xac0 net/socket.c:1788
 __do_sys_sendto net/socket.c:1800 [inline]
 __se_sys_sendto+0x107/0x130 net/socket.c:1796
 __x64_sys_sendto+0x6e/0x90 net/socket.c:1796
 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 4-7 of 28 are uninitialized
Memory access of size 28 starts at ffff88804b83fce0
Data copied to user address 0000000020000000
==================================================================