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BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x17ad/0x1ee0 net/core/dev.c:4884
 bpf_prog_run_generic_xdp+0x17ad/0x1ee0 net/core/dev.c:4884
 netif_receive_generic_xdp net/core/dev.c:4964 [inline]
 do_xdp_generic+0xb68/0x1440 net/core/dev.c:5023
 tun_get_user+0x4bcd/0x69e0 drivers/net/tun.c:1924
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2110 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xb63/0x1520 fs/read_write.c:590
 ksys_write+0x20f/0x4c0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x93/0xe0 fs/read_write.c:652
 x64_sys_call+0x3062/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 pskb_expand_head+0x30f/0x19d0 net/core/skbuff.c:2253
 netif_skb_check_for_xdp net/core/dev.c:4927 [inline]
 netif_receive_generic_xdp net/core/dev.c:4958 [inline]
 do_xdp_generic+0x931/0x1440 net/core/dev.c:5023
 tun_get_user+0x4bcd/0x69e0 drivers/net/tun.c:1924
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2110 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xb63/0x1520 fs/read_write.c:590
 ksys_write+0x20f/0x4c0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x93/0xe0 fs/read_write.c:652
 x64_sys_call+0x3062/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 __do_kmalloc_node mm/slub.c:3965 [inline]
 __kmalloc_node_track_caller+0x747/0x1060 mm/slub.c:3986
 kmalloc_reserve+0x249/0x4a0 net/core/skbuff.c:599
 __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1313 [inline]
 alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504
 sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795
 tun_alloc_skb drivers/net/tun.c:1525 [inline]
 tun_get_user+0x209a/0x69e0 drivers/net/tun.c:1846
 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
 call_write_iter include/linux/fs.h:2110 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xb63/0x1520 fs/read_write.c:590
 ksys_write+0x20f/0x4c0 fs/read_write.c:643
 __do_sys_write fs/read_write.c:655 [inline]
 __se_sys_write fs/read_write.c:652 [inline]
 __x64_sys_write+0x93/0xe0 fs/read_write.c:652
 x64_sys_call+0x3062/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 PID: 5422 Comm: syz-executor.4 Not tainted 6.9.0-rc4-syzkaller-00274-g3b68086599f8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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