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BUG: KMSAN: uninit-value in __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:60 [inline]
BUG: KMSAN: uninit-value in ip6_flow_hdr include/net/ipv6.h:941 [inline]
BUG: KMSAN: uninit-value in udp_tunnel6_xmit_skb+0xbee/0xf60 net/ipv6/ip6_udp_tunnel.c:102
CPU: 0 PID: 25674 Comm: syz-executor.3 Tainted: G        W         5.11.0-rc7-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+0x21c/0x280 lib/dump_stack.c:120
 kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x5f/0xa0 mm/kmsan/kmsan_instr.c:197
 __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
 __fswab32 include/uapi/linux/swab.h:60 [inline]
 ip6_flow_hdr include/net/ipv6.h:941 [inline]
 udp_tunnel6_xmit_skb+0xbee/0xf60 net/ipv6/ip6_udp_tunnel.c:102
 geneve6_xmit_skb drivers/net/geneve.c:1027 [inline]
 geneve_xmit+0x3351/0x3c20 drivers/net/geneve.c:1056
 __netdev_start_xmit include/linux/netdevice.h:4778 [inline]
 netdev_start_xmit include/linux/netdevice.h:4792 [inline]
 __dev_direct_xmit+0x9bc/0xcb0 net/core/dev.c:4219
 dev_direct_xmit include/linux/netdevice.h:2857 [inline]
 packet_direct_xmit+0x329/0x540 net/packet/af_packet.c:244
 packet_snd net/packet/af_packet.c:3006 [inline]
 packet_sendmsg+0x8778/0x9a60 net/packet/af_packet.c:3031
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0xcfc/0x12f0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0xa57/0x1010 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2515
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2515
 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x465f69
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:00007f4ba3b4e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465f69
RDX: 0000000000000001 RSI: 0000000020000bc0 RDI: 0000000000000003
RBP: 00000000004bfa8f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 0000000000a9fb1f R14: 00007f4ba3b4e300 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+0x8d/0xe0 mm/kmsan/kmsan_hooks.c:76
 slab_alloc_node mm/slub.c:2907 [inline]
 __kmalloc_node_track_caller+0xa37/0x1430 mm/slub.c:4527
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0x2f8/0xb30 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1099 [inline]
 alloc_skb_with_frags+0x1f3/0xc10 net/core/skbuff.c:5894
 sock_alloc_send_pskb+0xdc1/0xf90 net/core/sock.c:2348
 packet_alloc_skb net/packet/af_packet.c:2854 [inline]
 packet_snd net/packet/af_packet.c:2949 [inline]
 packet_sendmsg+0x6aab/0x9a60 net/packet/af_packet.c:3031
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0xcfc/0x12f0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0xa57/0x1010 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg+0xbd/0xe0 net/socket.c:2515
 __x64_sys_sendmmsg+0x56/0x70 net/socket.c:2515
 do_syscall_64+0x9f/0x140 arch/x86/entry/common.c:48
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
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