syzbot

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: uninit-value in ip6_parse_tlv+0x8d5/0xcd0 net/ipv6/exthdrs.c:172
CPU: 1 PID: 4535 Comm: syz-executor786 Not tainted 4.17.0-rc3+ #88
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
 ip6_parse_tlv+0x8d5/0xcd0 net/ipv6/exthdrs.c:172
 ipv6_destopt_rcv+0x50d/0xd90 net/ipv6/exthdrs.c:310
 ip6_input_finish+0xaac/0x2250 net/ipv6/ip6_input.c:284
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ip6_input net/ipv6/ip6_input.c:327 [inline]
 ip6_mc_input+0xa67/0x1080 net/ipv6/ip6_input.c:404
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x46e/0x6e0 net/ipv6/ip6_input.c:71
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ipv6_rcv+0x1e16/0x2340 net/ipv6/ip6_input.c:208
 __netif_receive_skb_core+0x47df/0x4a90 net/core/dev.c:4592
 __netif_receive_skb net/core/dev.c:4657 [inline]
 process_backlog+0x62d/0xe20 net/core/dev.c:5337
 napi_poll net/core/dev.c:5735 [inline]
 net_rx_action+0x7c1/0x1a70 net/core/dev.c:5801
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1046
 </IRQ>
 do_softirq+0xb6/0xf0 kernel/softirq.c:329
 netif_rx_ni net/core/dev.c:4219 [inline]
 dev_loopback_xmit+0x8b0/0x900 net/core/dev.c:3347
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ip6_finish_output2+0x1e24/0x2110 net/ipv6/ip6_output.c:84
 ip6_finish_output+0xae9/0xba0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip6_output+0x597/0x6c0 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:444 [inline]
 ip6_local_out+0x15e/0x1d0 net/ipv6/output_core.c:176
 ip6_send_skb net/ipv6/ip6_output.c:1702 [inline]
 ip6_push_pending_frames+0x218/0x4d0 net/ipv6/ip6_output.c:1722
 rawv6_push_pending_frames net/ipv6/raw.c:616 [inline]
 rawv6_sendmsg+0x4235/0x4fb0 net/ipv6/raw.c:935
 inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg net/socket.c:639 [inline]
 __sys_sendto+0x6c0/0x7e0 net/socket.c:1789
 __do_sys_sendto net/socket.c:1801 [inline]
 __se_sys_sendto net/socket.c:1797 [inline]
 __x64_sys_sendto+0x1a1/0x210 net/socket.c:1797
 do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x43fe79
RSP: 002b:00007ffc475970d8 EFLAGS: 00000216 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fe79
RDX: 0000000000000000 RSI: 0000000020001ffe RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000020003000 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004017a0
R13: 0000000000401830 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan.c:321
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2753 [inline]
 __kmalloc_node_track_caller+0xb32/0x11b0 mm/slub.c:4395
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:988 [inline]
 alloc_skb_with_frags+0x1e6/0xb80 net/core/skbuff.c:5254
 sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2088
 sock_alloc_send_skb+0xca/0xe0 net/core/sock.c:2105
 __ip6_append_data+0x33a2/0x4e40 net/ipv6/ip6_output.c:1427
 ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1596
 rawv6_sendmsg+0x2740/0x4fb0 net/ipv6/raw.c:928
 inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg net/socket.c:639 [inline]
 __sys_sendto+0x6c0/0x7e0 net/socket.c:1789
 __do_sys_sendto net/socket.c:1801 [inline]
 __se_sys_sendto net/socket.c:1797 [inline]
 __x64_sys_sendto+0x1a1/0x210 net/socket.c:1797
 do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
==================================================================