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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: 10429 Comm: syz-executor4 Not tainted 4.19.0-rc1+ #41
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+0x14b/0x190 lib/dump_stack.c:113
 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956
 kmsan_internal_check_memory+0x138/0x1f0 mm/kmsan/kmsan.c:1001
 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+0x41f/0xf20 net/core/datagram.c:431
 skb_copy_datagram_msg include/linux/skbuff.h:3279 [inline]
 packet_recvmsg+0x725/0x1c30 net/packet/af_packet.c:3324
 sock_recvmsg_nosec net/socket.c:794 [inline]
 sock_recvmsg+0x1d6/0x230 net/socket.c:801
 ___sys_recvmsg+0x426/0xa60 net/socket.c:2276
 __sys_recvmsg net/socket.c:2325 [inline]
 __do_sys_recvmsg net/socket.c:2335 [inline]
 __se_sys_recvmsg+0x298/0x3c0 net/socket.c:2332
 __x64_sys_recvmsg+0x4a/0x70 net/socket.c:2332
 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457099
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:00007f47bc492c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00007f47bc4936d4 RCX: 0000000000457099
RDX: 0000000000000062 RSI: 0000000020000800 RDI: 0000000000000006
RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d42f0 R14: 00000000004c8adb R15: 0000000000000001

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:2719 [inline]
 __kmalloc_node_track_caller+0x9e7/0x1160 mm/slub.c:4352
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2f5/0x9e0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:996 [inline]
 sock_wmalloc+0x13e/0x6b0 net/core/sock.c:1934
 pppoe_sendmsg+0x40e/0xb50 drivers/net/ppp/pppoe.c:867
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg net/socket.c:631 [inline]
 ___sys_sendmsg+0xe70/0x1290 net/socket.c:2114
 __sys_sendmmsg+0x4ac/0x930 net/socket.c:2209
 __do_sys_sendmmsg net/socket.c:2238 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2235
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2235
 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Bytes 4-5 of 50 are uninitialized
Memory access starts at ffff88010eb7da64
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