=====================================================
BUG: KMSAN: uninit-value in ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:831 [inline]
BUG: KMSAN: uninit-value in ip6gre_tunnel_xmit+0xfee/0x1cf0 net/ipv6/ip6_gre.c:894
 ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:831 [inline]
 ip6gre_tunnel_xmit+0xfee/0x1cf0 net/ipv6/ip6_gre.c:894
 __netdev_start_xmit include/linux/netdevice.h:5248 [inline]
 netdev_start_xmit include/linux/netdevice.h:5257 [inline]
 xmit_one net/core/dev.c:3845 [inline]
 dev_hard_start_xmit+0x22f/0xa30 net/core/dev.c:3861
 sch_direct_xmit+0x3b2/0xcf0 net/sched/sch_generic.c:344
 __dev_xmit_skb net/core/dev.c:4152 [inline]
 __dev_queue_xmit+0x3588/0x5e60 net/core/dev.c:4729
 dev_queue_xmit include/linux/netdevice.h:3365 [inline]
 br_dev_queue_push_xmit+0xa12/0xc20 net/bridge/br_forward.c:53
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_forward_finish+0xfe/0x330 net/bridge/br_forward.c:66
 NF_HOOK include/linux/netfilter.h:318 [inline]
 __br_forward+0x8cc/0xb30 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0x3e8/0x590 net/bridge/br_forward.c:191
 br_flood+0x45b/0xb70 net/bridge/br_forward.c:238
 br_handle_frame_finish+0x2af2/0x2e60 net/bridge/br_input.c:229
 nf_hook_bridge_pre net/bridge/br_input.c:313 [inline]
 br_handle_frame+0x1837/0x2190 net/bridge/br_input.c:442
 __netif_receive_skb_core+0x2043/0x7150 net/core/dev.c:5966
 __netif_receive_skb_one_core net/core/dev.c:6077 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6192
 netif_receive_skb_internal net/core/dev.c:6278 [inline]
 netif_receive_skb+0x57/0x630 net/core/dev.c:6337
 tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
 tun_get_user+0x5d60/0x6d70 drivers/net/tun.c:1953
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe2/0x15d0 fs/read_write.c:686
 ksys_write fs/read_write.c:738 [inline]
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746
 x64_sys_call+0x3014/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4969 [inline]
 slab_alloc_node mm/slub.c:5272 [inline]
 kmem_cache_alloc_node_noprof+0x989/0x16b0 mm/slub.c:5324
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579
 pskb_expand_head+0x1fc/0x1610 net/core/skbuff.c:2241
 __skb_cow include/linux/skbuff.h:3853 [inline]
 skb_cow_head include/linux/skbuff.h:3887 [inline]
 __vlan_insert_inner_tag include/linux/if_vlan.h:360 [inline]
 vlan_insert_inner_tag include/linux/if_vlan.h:433 [inline]
 vlan_insert_tag include/linux/if_vlan.h:460 [inline]
 vlan_insert_tag_set_proto include/linux/if_vlan.h:481 [inline]
 __vlan_hwaccel_push_inside include/linux/if_vlan.h:521 [inline]
 validate_xmit_vlan net/core/dev.c:3884 [inline]
 validate_xmit_skb+0x607/0x1d50 net/core/dev.c:3986
 validate_xmit_skb_list+0xd4/0x320 net/core/dev.c:4047
 sch_direct_xmit+0xd4/0xcf0 net/sched/sch_generic.c:329
 __dev_xmit_skb net/core/dev.c:4152 [inline]
 __dev_queue_xmit+0x3588/0x5e60 net/core/dev.c:4729
 dev_queue_xmit include/linux/netdevice.h:3365 [inline]
 br_dev_queue_push_xmit+0xa12/0xc20 net/bridge/br_forward.c:53
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_forward_finish+0xfe/0x330 net/bridge/br_forward.c:66
 NF_HOOK include/linux/netfilter.h:318 [inline]
 __br_forward+0x8cc/0xb30 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0x3e8/0x590 net/bridge/br_forward.c:191
 br_flood+0x45b/0xb70 net/bridge/br_forward.c:238
 br_handle_frame_finish+0x2af2/0x2e60 net/bridge/br_input.c:229
 nf_hook_bridge_pre net/bridge/br_input.c:313 [inline]
 br_handle_frame+0x1837/0x2190 net/bridge/br_input.c:442
 __netif_receive_skb_core+0x2043/0x7150 net/core/dev.c:5966
 __netif_receive_skb_one_core net/core/dev.c:6077 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6192
 netif_receive_skb_internal net/core/dev.c:6278 [inline]
 netif_receive_skb+0x57/0x630 net/core/dev.c:6337
 tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
 tun_get_user+0x5d60/0x6d70 drivers/net/tun.c:1953
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe2/0x15d0 fs/read_write.c:686
 ksys_write fs/read_write.c:738 [inline]
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746
 x64_sys_call+0x3014/0x3e30 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 6484 Comm: syz.0.16 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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