==================================================================
BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x44f/0x27d0 lib/iov_iter.c:571
CPU: 1 PID: 7182 Comm: syz-executor0 Not tainted 4.18.0-rc8+ #33
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+0x17c/0x1c0 lib/dump_stack.c:113
 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:982
 kmsan_internal_check_memory+0x138/0x1f0 mm/kmsan/kmsan.c:1027
 kmsan_copy_to_user+0x73/0xb0 mm/kmsan/kmsan_hooks.c:479
 copyout lib/iov_iter.c:140 [inline]
 _copy_to_iter+0x44f/0x27d0 lib/iov_iter.c:571
 copy_to_iter include/linux/uio.h:106 [inline]
 skb_copy_datagram_iter+0x422/0xfa0 net/core/datagram.c:431
 skb_copy_datagram_msg include/linux/skbuff.h:3270 [inline]
 packet_recvmsg+0x728/0x1c30 net/packet/af_packet.c:3320
 sock_recvmsg_nosec net/socket.c:815 [inline]
 sock_recvmsg net/socket.c:822 [inline]
 sock_read_iter+0x406/0x480 net/socket.c:899
 call_read_iter include/linux/fs.h:1787 [inline]
 new_sync_read fs/read_write.c:406 [inline]
 __vfs_read+0x7b9/0x9f0 fs/read_write.c:418
 vfs_read+0x36c/0x6b0 fs/read_write.c:452
 ksys_read fs/read_write.c:578 [inline]
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x1b7/0x3c0 fs/read_write.c:586
 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457089
Code: fd b4 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 b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007fa90a259c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fa90a25a6d4 RCX: 0000000000457089
RDX: 0000000000000019 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d3228 R14: 00000000004c781a R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181
 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91
 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan_hooks.c:100
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2720 [inline]
 __kmalloc_node_track_caller+0xb4c/0x11d0 mm/slub.c:4353
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2ce/0x9b0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:988 [inline]
 alloc_skb_with_frags+0x1d0/0xac0 net/core/skbuff.c:5272
 sock_alloc_send_pskb+0xb47/0x1120 net/core/sock.c:2095
 packet_alloc_skb net/packet/af_packet.c:2776 [inline]
 packet_snd net/packet/af_packet.c:2867 [inline]
 packet_sendmsg+0x6480/0x8ae0 net/packet/af_packet.c:2946
 sock_sendmsg_nosec net/socket.c:642 [inline]
 sock_sendmsg net/socket.c:652 [inline]
 ___sys_sendmsg+0xe32/0x1250 net/socket.c:2126
 __sys_sendmmsg+0x4ac/0x930 net/socket.c:2221
 __do_sys_sendmmsg net/socket.c:2250 [inline]
 __se_sys_sendmmsg net/socket.c:2247 [inline]
 __x64_sys_sendmmsg+0x11c/0x170 net/socket.c:2247
 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 4-5 of 25 are uninitialized
Memory access starts at ffff8801307b2a64
==================================================================