syzbot

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BUG: KMSAN: uninit-value in ipv6_frag_rcv+0xfa5/0x6970 net/ipv6/reassembly.c:551
CPU: 0 PID: 3580 Comm: syzkaller433171 Not tainted 4.16.0+ #82
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __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
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676
 ipv6_frag_rcv+0xfa5/0x6970 net/ipv6/reassembly.c:551
 ip6_input_finish+0xa62/0x2110 net/ipv6/ip6_input.c:284
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ip6_input+0x294/0x320 net/ipv6/ip6_input.c:327
 dst_input include/net/dst.h:449 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:71 [inline]
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ipv6_rcv+0x20ec/0x26d0 net/ipv6/ip6_input.c:208
 __netif_receive_skb_core+0x47cf/0x4a80 net/core/dev.c:4562
 __netif_receive_skb net/core/dev.c:4627 [inline]
 process_backlog+0x62d/0xe20 net/core/dev.c:5307
 napi_poll net/core/dev.c:5705 [inline]
 net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1040
 </IRQ>
 do_softirq kernel/softirq.c:329 [inline]
 __local_bh_enable_ip+0x114/0x140 kernel/softirq.c:182
 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline]
 ip6_finish_output2+0x1b6c/0x1f20 net/ipv6/ip6_output.c:121
 ip6_finish_output+0xb3f/0xc00 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:443 [inline]
 ip6_local_out+0x573/0x640 net/ipv6/output_core.c:176
 ip6_send_skb net/ipv6/ip6_output.c:1682 [inline]
 ip6_push_pending_frames+0x218/0x4d0 net/ipv6/ip6_output.c:1702
 rawv6_push_pending_frames net/ipv6/raw.c:616 [inline]
 rawv6_sendmsg+0x4500/0x4cc0 net/ipv6/raw.c:935
 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]
 sock_write_iter+0x3b9/0x470 net/socket.c:909
 do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776
 do_iter_write+0x30d/0xd40 fs/read_write.c:932
 vfs_writev fs/read_write.c:977 [inline]
 do_writev+0x3c9/0x830 fs/read_write.c:1012
 SYSC_writev+0x9b/0xb0 fs/read_write.c:1085
 SyS_writev+0x56/0x80 fs/read_write.c:1082
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x43ffa9
RSP: 002b:00007fffcb5f67c8 EFLAGS: 00000217 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ffa9
RDX: 0000000000000001 RSI: 0000000020001c40 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000217 R12: 00000000004018d0
R13: 0000000000401960 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:293 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:684
 kmsan_memcpy_origins+0x11d/0x170 mm/kmsan/kmsan.c:526
 __msan_memcpy+0x19f/0x1f0 mm/kmsan/kmsan_instr.c:470
 skb_copy_bits+0x63a/0xdb0 net/core/skbuff.c:2046
 __pskb_pull_tail+0x483/0x22e0 net/core/skbuff.c:1883
 pskb_may_pull include/linux/skbuff.h:2112 [inline]
 ipv6_frag_rcv+0x1894/0x6970 net/ipv6/reassembly.c:544
 ip6_input_finish+0xa62/0x2110 net/ipv6/ip6_input.c:284
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ip6_input+0x294/0x320 net/ipv6/ip6_input.c:327
 dst_input include/net/dst.h:449 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:71 [inline]
 NF_HOOK include/linux/netfilter.h:288 [inline]
 ipv6_rcv+0x20ec/0x26d0 net/ipv6/ip6_input.c:208
 __netif_receive_skb_core+0x47cf/0x4a80 net/core/dev.c:4562
 __netif_receive_skb net/core/dev.c:4627 [inline]
 process_backlog+0x62d/0xe20 net/core/dev.c:5307
 napi_poll net/core/dev.c:5705 [inline]
 net_rx_action+0x7c1/0x1a70 net/core/dev.c:5771
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
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
 __ip6_append_data+0x1a20/0x4bb0 net/ipv6/ip6_output.c:1503
 ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1576
 rawv6_sendmsg+0x2787/0x4cc0 net/ipv6/raw.c:928
 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]
 sock_write_iter+0x3b9/0x470 net/socket.c:909
 do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776
 do_iter_write+0x30d/0xd40 fs/read_write.c:932
 vfs_writev fs/read_write.c:977 [inline]
 do_writev+0x3c9/0x830 fs/read_write.c:1012
 SYSC_writev+0x9b/0xb0 fs/read_write.c:1085
 SyS_writev+0x56/0x80 fs/read_write.c:1082
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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