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BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x1960/0x1f60 net/core/dev.c:5464
 bpf_prog_run_generic_xdp+0x1960/0x1f60 net/core/dev.c:5464
 netif_receive_generic_xdp net/core/dev.c:5547 [inline]
 do_xdp_generic+0xd51/0x1690 net/core/dev.c:5609
 tun_get_user+0x525a/0x7830 drivers/net/tun.c:1872
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:686
 ksys_write+0x1d9/0x470 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __ia32_sys_write+0x9a/0xf0 fs/read_write.c:746
 ia32_sys_call+0x3d5e/0x4340 arch/x86/include/generated/asm/syscalls_32.h:5
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 do_int80_emulation+0xeb/0x250 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1f/0x30 arch/x86/include/asm/idtentry.h:621

Uninit was stored to memory at:
 pskb_expand_head+0x317/0x1900 net/core/skbuff.c:2291
 netif_skb_check_for_xdp net/core/dev.c:5510 [inline]
 netif_receive_generic_xdp net/core/dev.c:5541 [inline]
 do_xdp_generic+0xa78/0x1690 net/core/dev.c:5609
 tun_get_user+0x525a/0x7830 drivers/net/tun.c:1872
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:686
 ksys_write+0x1d9/0x470 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __ia32_sys_write+0x9a/0xf0 fs/read_write.c:746
 ia32_sys_call+0x3d5e/0x4340 arch/x86/include/generated/asm/syscalls_32.h:5
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 do_int80_emulation+0xeb/0x250 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1f/0x30 arch/x86/include/asm/idtentry.h:621

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4960 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0xb6e/0x1c70 mm/slub.c:5768
 kmalloc_reserve+0x22f/0x4b0 net/core/skbuff.c:608
 __alloc_skb+0x805/0x1030 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6715
 sock_alloc_send_pskb+0xacb/0xc60 net/core/sock.c:2995
 tun_alloc_skb drivers/net/tun.c:1461 [inline]
 tun_get_user+0xcfc/0x7830 drivers/net/tun.c:1794
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:686
 ksys_write+0x1d9/0x470 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __ia32_sys_write+0x9a/0xf0 fs/read_write.c:746
 ia32_sys_call+0x3d5e/0x4340 arch/x86/include/generated/asm/syscalls_32.h:5
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 do_int80_emulation+0xeb/0x250 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1f/0x30 arch/x86/include/asm/idtentry.h:621

CPU: 0 UID: 0 PID: 9634 Comm: syz.7.873 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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