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BUG: KMSAN: uninit-value in eth_skb_pkt_type include/linux/etherdevice.h:628 [inline]
BUG: KMSAN: uninit-value in eth_type_trans+0x7af/0x9a0 net/ethernet/eth.c:165
 eth_skb_pkt_type include/linux/etherdevice.h:628 [inline]
 eth_type_trans+0x7af/0x9a0 net/ethernet/eth.c:165
 bpf_prog_run_generic_xdp+0x12a0/0x1ff0 net/core/dev.c:5297
 netif_receive_generic_xdp net/core/dev.c:5376 [inline]
 do_xdp_generic+0xd52/0x1690 net/core/dev.c:5438
 tun_get_user+0x447a/0x6b40 drivers/net/tun.c:1860
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xb4b/0x1580 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+0x38c3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 pskb_expand_head+0x310/0x1610 net/core/skbuff.c:2249
 netif_skb_check_for_xdp net/core/dev.c:5339 [inline]
 netif_receive_generic_xdp net/core/dev.c:5370 [inline]
 do_xdp_generic+0xa79/0x1690 net/core/dev.c:5438
 tun_get_user+0x447a/0x6b40 drivers/net/tun.c:1860
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xb4b/0x1580 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+0x38c3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 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:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_node_track_caller_noprof+0x96d/0x12f0 mm/slub.c:4347
 kmalloc_reserve+0x22f/0x4b0 net/core/skbuff.c:601
 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1336 [inline]
 alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6668
 sock_alloc_send_pskb+0xad8/0xc70 net/core/sock.c:2999
 tun_alloc_skb drivers/net/tun.c:1461 [inline]
 tun_get_user+0x1019/0x6b40 drivers/net/tun.c:1782
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xb4b/0x1580 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+0x38c3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 7313 Comm: syz.4.346 Not tainted 6.16.0-rc1-syzkaller-00239-g08215f5486ec #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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