IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
==================================================================
BUG: KMSAN: uninit-value in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
BUG: KMSAN: uninit-value in copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
CPU: 0 PID: 3947 Comm: syzkaller410853 Not tainted 4.16.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 kmsan_internal_check_memory+0x174/0x1e0 mm/kmsan/kmsan.c:1176
 kmsan_copy_to_user+0x69/0x160 mm/kmsan/kmsan.c:1199
 copyout lib/iov_iter.c:140 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
 copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
 skb_copy_datagram_iter+0x7fd/0xf70 net/core/datagram.c:450
 skb_copy_datagram_msg include/linux/skbuff.h:3264 [inline]
 udp_recvmsg+0x1072/0x1d90 net/ipv4/udp.c:1611
 inet_recvmsg+0x4c2/0x5f0 net/ipv4/af_inet.c:796
 sock_recvmsg_nosec net/socket.c:803 [inline]
 sock_recvmsg net/socket.c:810 [inline]
 sock_read_iter+0x405/0x480 net/socket.c:887
 call_read_iter include/linux/fs.h:1776 [inline]
 new_sync_read fs/read_write.c:401 [inline]
 __vfs_read+0x6fb/0x8e0 fs/read_write.c:413
 vfs_read+0x36c/0x6c0 fs/read_write.c:447
 SYSC_read+0x172/0x360 fs/read_write.c:573
 SyS_read+0x55/0x80 fs/read_write.c:566
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x446e39
RSP: 002b:00007fd88b536d48 EFLAGS: 00000297 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000006dcc24 RCX: 0000000000446e39
RDX: 00000000000000bc RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 174935bb5cfe020c
R13: 7efee79d8927f3fb R14: 00007fd88b5379c0 R15: 0000000000002710

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:814
 kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:868
 __alloc_pages_nodemask+0xf5b/0x5dc0 mm/page_alloc.c:4283
 alloc_pages_current+0x6b5/0x970 mm/mempolicy.c:2055
 alloc_pages include/linux/gfp.h:494 [inline]
 skb_page_frag_refill+0x3ba/0x5e0 net/core/sock.c:2208
 sk_page_frag_refill+0xa4/0x340 net/core/sock.c:2228
 __ip_append_data+0x107e/0x3d10 net/ipv4/ip_output.c:1057
 ip_append_data+0x2fb/0x440 net/ipv4/ip_output.c:1170
 udp_sendmsg+0x746/0x3180 net/ipv4/udp.c:1070
 inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:764
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg net/socket.c:640 [inline]
 SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747
 SyS_sendto+0x8a/0xb0 net/socket.c:1715
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Bytes 0-55 of 56 are uninitialized
==================================================================