=====================================================
BUG: KMSAN: uninit-value in virtio_net_hdr_to_skb+0x1414/0x14f0 include/linux/virtio_net.h:86
CPU: 0 PID: 12189 Comm: syz-executor.2 Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x24c/0x2e0 lib/dump_stack.c:120
 kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:121
 __msan_warning+0x5c/0xa0 mm/kmsan/kmsan_instr.c:197
 virtio_net_hdr_to_skb+0x1414/0x14f0 include/linux/virtio_net.h:86
 packet_snd net/packet/af_packet.c:2994 [inline]
 packet_sendmsg+0x85b8/0x99d0 net/packet/af_packet.c:3031
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0xcfc/0x12f0 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmsg+0x714/0x830 net/socket.c:2433
 __do_sys_sendmsg net/socket.c:2442 [inline]
 __se_sys_sendmsg+0x97/0xb0 net/socket.c:2440
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2440
 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7e626b3188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000000000003
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 0000000000a9fb1f R14: 00007f7e626b3300 R15: 0000000000022000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:121 [inline]
 kmsan_internal_poison_shadow+0x5c/0xf0 mm/kmsan/kmsan.c:104
 kmsan_slab_alloc+0x8e/0xe0 mm/kmsan/kmsan_hooks.c:76
 slab_alloc_node mm/slub.c:2922 [inline]
 slab_alloc mm/slub.c:2931 [inline]
 kmem_cache_alloc_trace+0x8c7/0x1030 mm/slub.c:2948
 kmalloc include/linux/slab.h:554 [inline]
 __hw_addr_create_ex net/core/dev_addr_lists.c:30 [inline]
 __hw_addr_add_ex net/core/dev_addr_lists.c:76 [inline]
 __hw_addr_add net/core/dev_addr_lists.c:84 [inline]
 dev_addr_init+0x369/0x910 net/core/dev_addr_lists.c:464
 alloc_netdev_mqs+0x326/0x1940 net/core/dev.c:10705
 __ip_tunnel_create+0x412/0x760 net/ipv4/ip_tunnel.c:254
 ip_tunnel_init_net+0x53c/0xe70 net/ipv4/ip_tunnel.c:1060
 ipgre_tap_init_net+0x84/0x90 net/ipv4/ip_gre.c:1675
 ops_init+0x595/0x7e0 net/core/net_namespace.c:140
 setup_net+0x3ea/0x1560 net/core/net_namespace.c:333
 copy_net_ns+0x84c/0xc80 net/core/net_namespace.c:474
 create_new_namespaces+0x8c0/0x1270 kernel/nsproxy.c:110
 copy_namespaces+0x3cf/0x4f0 kernel/nsproxy.c:178
 copy_process+0x40b3/0x9b80 kernel/fork.c:2118
 kernel_clone+0x4ea/0x1350 kernel/fork.c:2502
 __do_sys_clone3 kernel/fork.c:2777 [inline]
 __se_sys_clone3+0x5a6/0x5c0 kernel/fork.c:2761
 __x64_sys_clone3+0x3e/0x60 kernel/fork.c:2761
 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48
 entry_SYSCALL_64_after_hwframe+0x44/0xae
=====================================================