=====================================================
BUG: KMSAN: uninit-value in ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:833 [inline]
BUG: KMSAN: uninit-value in ip6gre_tunnel_xmit+0xfee/0x1cf0 net/ipv6/ip6_gre.c:896
 ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:833 [inline]
 ip6gre_tunnel_xmit+0xfee/0x1cf0 net/ipv6/ip6_gre.c:896
 __netdev_start_xmit include/linux/netdevice.h:5273 [inline]
 netdev_start_xmit include/linux/netdevice.h:5282 [inline]
 xmit_one net/core/dev.c:3853 [inline]
 dev_hard_start_xmit+0x22f/0xa30 net/core/dev.c:3869
 sch_direct_xmit+0x3b2/0xcf0 net/sched/sch_generic.c:347
 __dev_xmit_skb net/core/dev.c:4169 [inline]
 __dev_queue_xmit+0x2f80/0x58e0 net/core/dev.c:4785
 dev_queue_xmit include/linux/netdevice.h:3381 [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+0x847/0xab0 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0x3e0/0x5c0 net/bridge/br_forward.c:191
 br_flood+0x45b/0xb70 net/bridge/br_forward.c:238
 br_handle_frame_finish+0x2a34/0x2dd0 net/bridge/br_input.c:229
 nf_hook_bridge_pre net/bridge/br_input.c:313 [inline]
 br_handle_frame+0x179f/0x2180 net/bridge/br_input.c:442
 __netif_receive_skb_core+0xf8c/0x4d10 net/core/dev.c:6026
 __netif_receive_skb_one_core net/core/dev.c:6137 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6252
 netif_receive_skb_internal net/core/dev.c:6338 [inline]
 netif_receive_skb+0x57/0x630 net/core/dev.c:6397
 tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
 tun_get_user+0x5c0e/0x6c60 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+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 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:4960 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_node_noprof+0x9e7/0x17a0 mm/slub.c:5315
 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:586
 pskb_expand_head+0x1fc/0x15d0 net/core/skbuff.c:2282
 __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:361 [inline]
 vlan_insert_inner_tag include/linux/if_vlan.h:434 [inline]
 vlan_insert_tag include/linux/if_vlan.h:461 [inline]
 vlan_insert_tag_set_proto include/linux/if_vlan.h:482 [inline]
 __vlan_hwaccel_push_inside include/linux/if_vlan.h:522 [inline]
 validate_xmit_vlan net/core/dev.c:3892 [inline]
 validate_xmit_skb+0x980/0x2400 net/core/dev.c:3994
 validate_xmit_skb_list+0xd4/0x320 net/core/dev.c:4055
 sch_direct_xmit+0xd4/0xcf0 net/sched/sch_generic.c:332
 __dev_xmit_skb net/core/dev.c:4169 [inline]
 __dev_queue_xmit+0x2f80/0x58e0 net/core/dev.c:4785
 dev_queue_xmit include/linux/netdevice.h:3381 [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+0x847/0xab0 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0x3e0/0x5c0 net/bridge/br_forward.c:191
 br_flood+0x45b/0xb70 net/bridge/br_forward.c:238
 br_handle_frame_finish+0x2a34/0x2dd0 net/bridge/br_input.c:229
 nf_hook_bridge_pre net/bridge/br_input.c:313 [inline]
 br_handle_frame+0x179f/0x2180 net/bridge/br_input.c:442
 __netif_receive_skb_core+0xf8c/0x4d10 net/core/dev.c:6026
 __netif_receive_skb_one_core net/core/dev.c:6137 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6252
 netif_receive_skb_internal net/core/dev.c:6338 [inline]
 netif_receive_skb+0x57/0x630 net/core/dev.c:6397
 tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
 tun_get_user+0x5c0e/0x6c60 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+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 6480 Comm: syz.0.16 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
=====================================================