syzbot

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BUG: KMSAN: uninit-value in __skb_flow_dissect_gre net/core/flow_dissector.c:338 [inline]
BUG: KMSAN: uninit-value in __skb_flow_dissect+0x401f/0x6580 net/core/flow_dissector.c:901
CPU: 0 PID: 3574 Comm: syzkaller776093 Not tainted 4.16.0+ #84
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:676
 __skb_flow_dissect_gre net/core/flow_dissector.c:338 [inline]
 __skb_flow_dissect+0x401f/0x6580 net/core/flow_dissector.c:901
 __skb_get_hash_symmetric+0x10b/0x230 net/core/flow_dissector.c:1217
 fanout_demux_hash net/packet/af_packet.c:1339 [inline]
 packet_rcv_fanout+0x38f/0x8d0 net/packet/af_packet.c:1454
 dev_queue_xmit_nit+0x111a/0x11e0 net/core/dev.c:1991
 xmit_one net/core/dev.c:3022 [inline]
 dev_hard_start_xmit+0x27c/0xc70 net/core/dev.c:3042
 __dev_queue_xmit+0x22d9/0x2b60 net/core/dev.c:3557
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590
 neigh_resolve_output+0xac6/0xb60 net/core/neighbour.c:1350
 neigh_output include/net/neighbour.h:482 [inline]
 ip_finish_output2+0x1238/0x1380 net/ipv4/ip_output.c:229
 ip_finish_output+0xcb0/0xff0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip_output+0x502/0x5c0 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:443 [inline]
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb+0x5f3/0x820 net/ipv4/ip_output.c:1414
 ip_push_pending_frames+0x105/0x170 net/ipv4/ip_output.c:1434
 raw_sendmsg+0x2960/0x3ed0 net/ipv4/raw.c:684
 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]
 SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747
 SyS_sendto+0x8a/0xb0 net/socket.c:1715
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x43ffc9
RSP: 002b:00007fffded673e8 EFLAGS: 00000217 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ffc9
RDX: 0000000000000004 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 0000000020000140 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004018f0
R13: 0000000000401980 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
 __skb_header_pointer include/linux/skbuff.h:3337 [inline]
 __skb_flow_dissect_gre net/core/flow_dissector.c:332 [inline]
 __skb_flow_dissect+0x3931/0x6580 net/core/flow_dissector.c:901
 __skb_get_hash_symmetric+0x10b/0x230 net/core/flow_dissector.c:1217
 fanout_demux_hash net/packet/af_packet.c:1339 [inline]
 packet_rcv_fanout+0x38f/0x8d0 net/packet/af_packet.c:1454
 dev_queue_xmit_nit+0x111a/0x11e0 net/core/dev.c:1991
 xmit_one net/core/dev.c:3022 [inline]
 dev_hard_start_xmit+0x27c/0xc70 net/core/dev.c:3042
 __dev_queue_xmit+0x22d9/0x2b60 net/core/dev.c:3557
 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590
 neigh_resolve_output+0xac6/0xb60 net/core/neighbour.c:1350
 neigh_output include/net/neighbour.h:482 [inline]
 ip_finish_output2+0x1238/0x1380 net/ipv4/ip_output.c:229
 ip_finish_output+0xcb0/0xff0 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip_output+0x502/0x5c0 net/ipv4/ip_output.c:405
 dst_output include/net/dst.h:443 [inline]
 ip_local_out net/ipv4/ip_output.c:124 [inline]
 ip_send_skb+0x5f3/0x820 net/ipv4/ip_output.c:1414
 ip_push_pending_frames+0x105/0x170 net/ipv4/ip_output.c:1434
 raw_sendmsg+0x2960/0x3ed0 net/ipv4/raw.c:684
 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]
 SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747
 SyS_sendto+0x8a/0xb0 net/socket.c:1715
 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_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
 __ip_append_data+0x107e/0x3d10 net/ipv4/ip_output.c:1057
 ip_append_data+0x2fb/0x440 net/ipv4/ip_output.c:1170
 raw_sendmsg+0x287b/0x3ed0 net/ipv4/raw.c:678
 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]
 SYSC_sendto+0x6c3/0x7e0 net/socket.c:1747
 SyS_sendto+0x8a/0xb0 net/socket.c:1715
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
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