==================================================================
BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x471/0x2640 lib/iov_iter.c:571
CPU: 1 PID: 16879 Comm: syz-executor0 Not tainted 4.19.0-rc8+ #70
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+0x306/0x460 lib/dump_stack.c:113
 kmsan_report+0x1a2/0x2e0 mm/kmsan/kmsan.c:917
 kmsan_internal_check_memory+0x2cd/0x460 mm/kmsan/kmsan.c:971
 kmsan_copy_to_user+0x89/0xe0 mm/kmsan/kmsan_hooks.c:552
 copyout lib/iov_iter.c:140 [inline]
 _copy_to_iter+0x471/0x2640 lib/iov_iter.c:571
 copy_to_iter include/linux/uio.h:106 [inline]
 skb_copy_datagram_iter+0x4c3/0x1040 net/core/datagram.c:431
 skb_copy_datagram_msg include/linux/skbuff.h:3279 [inline]
 packet_recvmsg+0x717/0x1c00 net/packet/af_packet.c:3327
 sock_recvmsg_nosec net/socket.c:794 [inline]
 sock_recvmsg+0x1d6/0x230 net/socket.c:801
 ___sys_recvmsg+0x459/0xae0 net/socket.c:2278
 __sys_recvmsg net/socket.c:2327 [inline]
 __do_sys_recvmsg net/socket.c:2337 [inline]
 __se_sys_recvmsg+0x2fc/0x450 net/socket.c:2334
 __x64_sys_recvmsg+0x4a/0x70 net/socket.c:2334
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457569
Code: fd b3 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 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f43a5b65c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000004
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f43a5b666d4
R13: 00000000004c324d R14: 00000000004d4e00 R15: 00000000ffffffff

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:255 [inline]
 kmsan_internal_poison_shadow+0xc8/0x1d0 mm/kmsan/kmsan.c:180
 kmsan_kmalloc+0xa4/0x120 mm/kmsan/kmsan_hooks.c:104
 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan_hooks.c:113
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2727 [inline]
 __kmalloc_node_track_caller+0xb43/0x1400 mm/slub.c:4360
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x422/0xe90 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:996 [inline]
 alloc_skb_with_frags+0x1d0/0xac0 net/core/skbuff.c:5275
 sock_alloc_send_pskb+0xe00/0x1420 net/core/sock.c:2082
 packet_alloc_skb net/packet/af_packet.c:2781 [inline]
 packet_snd net/packet/af_packet.c:2872 [inline]
 packet_sendmsg+0x6874/0x9170 net/packet/af_packet.c:2953
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xe47/0x1200 net/socket.c:2116
 __sys_sendmmsg+0x559/0xa50 net/socket.c:2211
 __do_sys_sendmmsg net/socket.c:2240 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2237
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2237
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 4-5 of 44 are uninitialized
Memory access of size 44 starts at ffff880136450864
==================================================================