=====================================================
BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321
 __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
 INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
 IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321
 ip6ip6_dscp_ecn_decapsulate+0x178/0x1b0 net/ipv6/ip6_tunnel.c:727
 __ip6_tnl_rcv+0xd4e/0x1590 net/ipv6/ip6_tunnel.c:845
 ip6_tnl_rcv+0xce/0x100 net/ipv6/ip6_tunnel.c:888
 gre_rcv+0x143f/0x1870
 ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438
 ip6_input_finish net/ipv6/ip6_input.c:483 [inline]
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492
 ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310
 __netif_receive_skb_one_core net/core/dev.c:5529 [inline]
 __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5643
 netif_receive_skb_internal net/core/dev.c:5729 [inline]
 netif_receive_skb+0x58/0x660 net/core/dev.c:5788
 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555
 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x8ef/0x1490 fs/read_write.c:584
 ksys_write+0x20f/0x4c0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x93/0xd0 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
 slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
 slab_alloc_node mm/slub.c:3478 [inline]
 kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
 __alloc_skb+0x318/0x740 net/core/skbuff.c:651
 alloc_skb include/linux/skbuff.h:1286 [inline]
 alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6331
 sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2780
 tun_alloc_skb drivers/net/tun.c:1531 [inline]
 tun_get_user+0x1e8a/0x66d0 drivers/net/tun.c:1846
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x8ef/0x1490 fs/read_write.c:584
 ksys_write+0x20f/0x4c0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x93/0xd0 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 1 PID: 15353 Comm: syz-executor.2 Not tainted 6.7.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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