syzbot

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BUG: KMSAN: uninit-value in __skb_checksum_complete+0x30e/0x430 net/core/datagram.c:756
CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.16.0+ #85
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __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:683
 __skb_checksum_complete+0x30e/0x430 net/core/datagram.c:756
 __skb_checksum_validate_complete include/linux/skbuff.h:3698 [inline]
 icmpv6_rcv+0xbfd/0x39b0 net/ipv6/icmp.c:833
 ip6_input_finish+0xaac/0x2250 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+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: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
 run_ksoftirqd+0x1f/0x40 kernel/softirq.c:666
 smpboot_thread_fn+0x488/0x970 kernel/smpboot.c:164
 kthread+0x539/0x720 kernel/kthread.c:239
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:406

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+0x109/0x160 mm/kmsan/kmsan_instr.c:477
 csum_partial_copy+0xbc/0x500 lib/checksum.c:178
 skb_copy_and_csum_bits+0x71a/0x1110 net/core/skbuff.c:2592
 icmpv6_getfrag+0x174/0x360 net/ipv6/icmp.c:303
 __ip6_append_data+0x3e34/0x4bc0 net/ipv6/ip6_output.c:1463
 ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1576
 icmp6_send+0x3168/0x3730 net/ipv6/icmp.c:574
 icmpv6_send+0xe0/0x110 net/ipv6/ip6_icmp.c:43
 ip6_link_failure+0x8f/0x580 net/ipv6/route.c:2034
 dst_link_failure include/net/dst.h:426 [inline]
 ndisc_error_report+0x101/0x1a0 net/ipv6/ndisc.c:695
 neigh_invalidate+0x385/0x930 net/core/neighbour.c:883
 neigh_timer_handler+0xd85/0x12d0 net/core/neighbour.c:969
 call_timer_fn+0x26a/0x5a0 kernel/time/timer.c:1326
 expire_timers kernel/time/timer.c:1363 [inline]
 __run_timers+0xda7/0x11c0 kernel/time/timer.c:1666
 run_timer_softirq+0x43/0x70 kernel/time/timer.c:1692
 __do_softirq+0x56d/0x93d kernel/softirq.c:285
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+0x109/0x160 mm/kmsan/kmsan_instr.c:477
 csum_partial_copy+0xbc/0x500 lib/checksum.c:178
 csum_and_copy_from_iter_full+0x107d/0x1a60 lib/iov_iter.c:1240
 ip_generic_getfrag+0x1f0/0x3b0 net/ipv4/ip_output.c:837
 __ip6_append_data+0x24fc/0x4bc0 net/ipv6/ip6_output.c:1518
 ip6_append_data+0x40e/0x6b0 net/ipv6/ip6_output.c:1576
 udpv6_sendmsg+0xfcc/0x47c0 net/ipv6/udp.c:1337
 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]
 kernel_sendmsg+0x228/0x2d0 net/socket.c:648
 sock_no_sendpage+0x1c8/0x250 net/core/sock.c:2578
 kernel_sendpage net/socket.c:3234 [inline]
 sock_sendpage+0x1de/0x2c0 net/socket.c:855
 pipe_to_sendpage+0x31b/0x430 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x49a/0xf30 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0x1c6/0x2a0 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x19b/0x200 fs/splice.c:1018
 splice_direct_to_actor+0x764/0x1040 fs/splice.c:973
 do_splice_direct+0x335/0x540 fs/splice.c:1061
 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413
 SYSC_sendfile64+0x1b3/0x300 fs/read_write.c:1468
 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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_vma+0xcc8/0x1800 mm/mempolicy.c:2019
 shmem_alloc_page mm/shmem.c:1471 [inline]
 shmem_alloc_and_acct_page+0x6d5/0x1000 mm/shmem.c:1496
 shmem_getpage_gfp+0x35db/0x5770 mm/shmem.c:1771
 shmem_getpage mm/shmem.c:131 [inline]
 shmem_file_read_iter+0x508/0x1180 mm/shmem.c:2456
 call_read_iter include/linux/fs.h:1776 [inline]
 generic_file_splice_read+0x5d2/0x900 fs/splice.c:307
 do_splice_to fs/splice.c:880 [inline]
 splice_direct_to_actor+0x4c6/0x1040 fs/splice.c:952
 do_splice_direct+0x335/0x540 fs/splice.c:1061
 do_sendfile+0x1067/0x1e40 fs/read_write.c:1413
 SYSC_sendfile64+0x1b3/0x300 fs/read_write.c:1468
 SyS_sendfile64+0x64/0x90 fs/read_write.c:1460
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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