=====================================================
BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x14a3/0x1ff0 net/core/dev.c:5291
 bpf_prog_run_generic_xdp+0x14a3/0x1ff0 net/core/dev.c:5291
 netif_receive_generic_xdp net/core/dev.c:5376 [inline]
 do_xdp_generic+0xd52/0x1690 net/core/dev.c:5438
 __netif_receive_skb_core+0x2533/0x70c0 net/core/dev.c:5788
 __netif_receive_skb_one_core net/core/dev.c:5975 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6090
 process_backlog+0x485/0xa00 net/core/dev.c:6442
 __napi_poll+0xda/0x9c0 net/core/dev.c:7414
 napi_poll net/core/dev.c:7478 [inline]
 net_rx_action+0xa59/0x1ac0 net/core/dev.c:7605
 handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
 __do_softirq+0x14/0x1b kernel/softirq.c:613
 do_softirq+0x99/0x100 kernel/softirq.c:480
 __local_bh_enable_ip+0xa1/0xb0 kernel/softirq.c:407
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 tun_rx_batched+0x889/0x980 drivers/net/tun.c:-1
 tun_get_user+0x4ee0/0x6b40 drivers/net/tun.c:1938
 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
 pskb_expand_head+0x1fc/0x1610 net/core/skbuff.c:2241
 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
 __netif_receive_skb_core+0x2533/0x70c0 net/core/dev.c:5788
 __netif_receive_skb_one_core net/core/dev.c:5975 [inline]
 __netif_receive_skb+0xcc/0xac0 net/core/dev.c:6090
 process_backlog+0x485/0xa00 net/core/dev.c:6442
 __napi_poll+0xda/0x9c0 net/core/dev.c:7414
 napi_poll net/core/dev.c:7478 [inline]
 net_rx_action+0xa59/0x1ac0 net/core/dev.c:7605
 handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
 __do_softirq+0x14/0x1b kernel/softirq.c:613

CPU: 1 UID: 0 PID: 27827 Comm: syz.2.8104 Tainted: G        W           6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(none) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
=====================================================