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BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x1a5a/0x2000 net/core/dev.c:5393
 bpf_prog_run_generic_xdp+0x1a5a/0x2000 net/core/dev.c:5393
 netif_receive_generic_xdp net/core/dev.c:5476 [inline]
 do_xdp_generic+0xd52/0x1690 net/core/dev.c:5538
 tun_get_user+0x45be/0x6d70 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+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]
 __ia32_sys_write+0x1f9/0x4d0 fs/read_write.c:746
 ia32_sys_call+0x35bc/0x4310 arch/x86/include/generated/asm/syscalls_32.h:5
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4962 [inline]
 slab_alloc_node mm/slub.c:5265 [inline]
 __do_kmalloc_node mm/slub.c:5626 [inline]
 __kmalloc_node_track_caller_noprof+0xb4b/0x1ba0 mm/slub.c:5736
 kmalloc_reserve+0x22f/0x4b0 net/core/skbuff.c:601
 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6671
 sock_alloc_send_pskb+0xacc/0xc60 net/core/sock.c:2965
 tun_alloc_skb drivers/net/tun.c:1461 [inline]
 tun_get_user+0x1142/0x6d70 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+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]
 __ia32_sys_write+0x1f9/0x4d0 fs/read_write.c:746
 ia32_sys_call+0x35bc/0x4310 arch/x86/include/generated/asm/syscalls_32.h:5
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 1 UID: 0 PID: 20158 Comm: syz.9.3705 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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