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BUG: KMSAN: uninit-value in ip_check_mc_rcu+0x2a5/0x670 /net/ipv4/igmp.c:2720
CPU: 1 PID: 17225 Comm: syz-executor.1 Not tainted 5.2.0+ #15
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+0x191/0x1f0 /lib/dump_stack.c:113
 kmsan_report+0x162/0x2d0 /mm/kmsan/kmsan_report.c:109
 __msan_warning+0x75/0xe0 /mm/kmsan/kmsan_instr.c:294
 ip_check_mc_rcu+0x2a5/0x670 /net/ipv4/igmp.c:2720
 __mkroute_output /net/ipv4/route.c:2318 [inline]
 ip_route_output_key_hash_rcu+0x1d44/0x3950 /net/ipv4/route.c:2597
 ip_route_output_key_hash /net/ipv4/route.c:2426 [inline]
 __ip_route_output_key /./include/net/route.h:125 [inline]
 ip_route_output_flow+0x1e2/0x3d0 /net/ipv4/route.c:2684
 ip_route_output_key /./include/net/route.h:135 [inline]
 ip_tunnel_xmit+0x127e/0x3320 /net/ipv4/ip_tunnel.c:753
 __gre_xmit /net/ipv4/ip_gre.c:444 [inline]
 ipgre_xmit+0xff3/0x1120 /net/ipv4/ip_gre.c:628
 __netdev_start_xmit /./include/linux/netdevice.h:4406 [inline]
 netdev_start_xmit /./include/linux/netdevice.h:4420 [inline]
 xmit_one /net/core/dev.c:3288 [inline]
 dev_hard_start_xmit+0x51a/0xab0 /net/core/dev.c:3304
 __dev_queue_xmit+0x394d/0x4270 /net/core/dev.c:3877
 dev_queue_xmit+0x4b/0x60 /net/core/dev.c:3910
 packet_snd /net/packet/af_packet.c:2941 [inline]
 packet_sendmsg+0x83f7/0x9290 /net/packet/af_packet.c:2966
 sock_sendmsg_nosec /net/socket.c:646 [inline]
 sock_sendmsg /net/socket.c:665 [inline]
 ___sys_sendmsg+0x12ff/0x13c0 /net/socket.c:2286
 __sys_sendmsg /net/socket.c:2324 [inline]
 __do_sys_sendmsg /net/socket.c:2333 [inline]
 __se_sys_sendmsg+0x305/0x460 /net/socket.c:2331
 __x64_sys_sendmsg+0x4a/0x70 /net/socket.c:2331
 do_syscall_64+0xbc/0xf0 /arch/x86/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x459819
Code: fd b7 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 b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2baeb91c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459819
RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2baeb926d4
R13: 00000000004c7560 R14: 00000000004dcac0 R15: 00000000ffffffff

Uninit was stored to memory at:
 kmsan_save_stack_with_flags /mm/kmsan/kmsan.c:187 [inline]
 kmsan_internal_chain_origin+0xcc/0x150 /mm/kmsan/kmsan.c:345
 __msan_chain_origin+0x6b/0xe0 /mm/kmsan/kmsan_instr.c:190
 ip_tunnel_init_flow /./include/net/ip_tunnels.h:248 [inline]
 ip_tunnel_xmit+0x9ee/0x3320 /net/ipv4/ip_tunnel.c:735
 __gre_xmit /net/ipv4/ip_gre.c:444 [inline]
 ipgre_xmit+0xff3/0x1120 /net/ipv4/ip_gre.c:628
 __netdev_start_xmit /./include/linux/netdevice.h:4406 [inline]
 netdev_start_xmit /./include/linux/netdevice.h:4420 [inline]
 xmit_one /net/core/dev.c:3288 [inline]
 dev_hard_start_xmit+0x51a/0xab0 /net/core/dev.c:3304
 __dev_queue_xmit+0x394d/0x4270 /net/core/dev.c:3877
 dev_queue_xmit+0x4b/0x60 /net/core/dev.c:3910
 packet_snd /net/packet/af_packet.c:2941 [inline]
 packet_sendmsg+0x83f7/0x9290 /net/packet/af_packet.c:2966
 sock_sendmsg_nosec /net/socket.c:646 [inline]
 sock_sendmsg /net/socket.c:665 [inline]
 ___sys_sendmsg+0x12ff/0x13c0 /net/socket.c:2286
 __sys_sendmsg /net/socket.c:2324 [inline]
 __do_sys_sendmsg /net/socket.c:2333 [inline]
 __se_sys_sendmsg+0x305/0x460 /net/socket.c:2331
 __x64_sys_sendmsg+0x4a/0x70 /net/socket.c:2331
 do_syscall_64+0xbc/0xf0 /arch/x86/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was stored to memory at:
 kmsan_save_stack_with_flags /mm/kmsan/kmsan.c:187 [inline]
 kmsan_internal_chain_origin+0xcc/0x150 /mm/kmsan/kmsan.c:345
 kmsan_memcpy_memmove_metadata+0x9f9/0xe00 /mm/kmsan/kmsan.c:278
 kmsan_memcpy_metadata+0xb/0x10 /mm/kmsan/kmsan.c:298
 __msan_memcpy+0x56/0x70 /mm/kmsan/kmsan_instr.c:129
 pskb_expand_head+0x38a/0x19f0 /net/core/skbuff.c:1510
 __skb_cow /./include/linux/skbuff.h:3036 [inline]
 skb_cow_head /./include/linux/skbuff.h:3070 [inline]
 ipgre_xmit+0x6d9/0x1120 /net/ipv4/ip_gre.c:607
 __netdev_start_xmit /./include/linux/netdevice.h:4406 [inline]
 netdev_start_xmit /./include/linux/netdevice.h:4420 [inline]
 xmit_one /net/core/dev.c:3288 [inline]
 dev_hard_start_xmit+0x51a/0xab0 /net/core/dev.c:3304
 __dev_queue_xmit+0x394d/0x4270 /net/core/dev.c:3877
 dev_queue_xmit+0x4b/0x60 /net/core/dev.c:3910
 packet_snd /net/packet/af_packet.c:2941 [inline]
 packet_sendmsg+0x83f7/0x9290 /net/packet/af_packet.c:2966
 sock_sendmsg_nosec /net/socket.c:646 [inline]
 sock_sendmsg /net/socket.c:665 [inline]
 ___sys_sendmsg+0x12ff/0x13c0 /net/socket.c:2286
 __sys_sendmsg /net/socket.c:2324 [inline]
 __do_sys_sendmsg /net/socket.c:2333 [inline]
 __se_sys_sendmsg+0x305/0x460 /net/socket.c:2331
 __x64_sys_sendmsg+0x4a/0x70 /net/socket.c:2331
 do_syscall_64+0xbc/0xf0 /arch/x86/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x63/0xe7

Uninit was created at:
 kmsan_save_stack_with_flags /mm/kmsan/kmsan.c:187 [inline]
 kmsan_internal_poison_shadow+0x53/0xa0 /mm/kmsan/kmsan.c:146
 kmsan_slab_alloc+0xaa/0x120 /mm/kmsan/kmsan_hooks.c:175
 slab_alloc_node /mm/slub.c:2771 [inline]
 __kmalloc_node_track_caller+0xc8f/0xf10 /mm/slub.c:4389
 __kmalloc_reserve /net/core/skbuff.c:138 [inline]
 __alloc_skb+0x306/0xa10 /net/core/skbuff.c:206
 alloc_skb /./include/linux/skbuff.h:1055 [inline]
 alloc_skb_with_frags+0x18c/0xa80 /net/core/skbuff.c:5328
 sock_alloc_send_pskb+0xafd/0x10a0 /net/core/sock.c:2219
 packet_alloc_skb /net/packet/af_packet.c:2789 [inline]
 packet_snd /net/packet/af_packet.c:2884 [inline]
 packet_sendmsg+0x6627/0x9290 /net/packet/af_packet.c:2966
 sock_sendmsg_nosec /net/socket.c:646 [inline]
 sock_sendmsg /net/socket.c:665 [inline]
 ___sys_sendmsg+0x12ff/0x13c0 /net/socket.c:2286
 __sys_sendmsg /net/socket.c:2324 [inline]
 __do_sys_sendmsg /net/socket.c:2333 [inline]
 __se_sys_sendmsg+0x305/0x460 /net/socket.c:2331
 __x64_sys_sendmsg+0x4a/0x70 /net/socket.c:2331
 do_syscall_64+0xbc/0xf0 /arch/x86/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
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