=====================================================
BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x11c2/0x20d0 net/core/dev.c:5474
 bpf_prog_run_generic_xdp+0x11c2/0x20d0 net/core/dev.c:5474
 netif_receive_generic_xdp net/core/dev.c:5559 [inline]
 do_xdp_generic+0xe07/0x17f0 net/core/dev.c:5621
 __netif_receive_skb_core+0x1a46/0x4dc0 net/core/dev.c:5974
 __netif_receive_skb_one_core net/core/dev.c:6162 [inline]
 __netif_receive_skb net/core/dev.c:6277 [inline]
 process_backlog+0x514/0x1500 net/core/dev.c:6628
 __napi_poll+0xdc/0x950 net/core/dev.c:7692
 napi_poll net/core/dev.c:7755 [inline]
 net_rx_action+0xa5b/0x1c70 net/core/dev.c:7912
 handle_softirqs+0x171/0x7e0 kernel/softirq.c:622
 __do_softirq+0x14/0x1b kernel/softirq.c:656
 do_softirq+0x58/0x90 kernel/softirq.c:523
 __local_bh_enable_ip+0xa1/0xb0 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 tun_rx_batched+0x887/0x980 drivers/net/tun.c:-1
 tun_get_user+0x6002/0x7830 drivers/net/tun.c:1953
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:688
 ksys_write+0x1d9/0x470 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __ia32_sys_write+0x9a/0xf0 fs/read_write.c:748
 ia32_sys_call+0x37a7/0x4360 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+0x15a/0x330 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1f/0x30 arch/x86/include/asm/idtentry.h:621

Uninit was created at:
 __alloc_frozen_pages_noprof+0x6f7/0x1020 mm/page_alloc.c:5273
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0x101/0x280 mm/mempolicy.c:2575
 skb_page_frag_refill+0x34e/0x730 net/core/sock.c:3146
 tun_build_skb drivers/net/tun.c:1620 [inline]
 tun_get_user+0x1d9a/0x7830 drivers/net/tun.c:1770
 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:688
 ksys_write+0x1d9/0x470 fs/read_write.c:740
 __do_sys_write fs/read_write.c:751 [inline]
 __se_sys_write fs/read_write.c:748 [inline]
 __ia32_sys_write+0x9a/0xf0 fs/read_write.c:748
 ia32_sys_call+0x37a7/0x4360 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+0x15a/0x330 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1f/0x30 arch/x86/include/asm/idtentry.h:621

CPU: 1 UID: 0 PID: 12551 Comm: syz.6.2056 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================