===================================================== BUG: KMSAN: uninit-value in bpf_prog_run_generic_xdp+0x1a74/0x1ff0 net/core/dev.c:5305 bpf_prog_run_generic_xdp+0x1a74/0x1ff0 net/core/dev.c:5305 netif_receive_generic_xdp net/core/dev.c:5388 [inline] do_xdp_generic+0xd52/0x1690 net/core/dev.c:5450 tun_get_user+0x45be/0x6ca0 drivers/net/tun.c:1872 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1996 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] __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746 x64_sys_call+0x3014/0x3e20 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 stored to memory at: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 11504 at kernel/stacktrace.c:29 stack_trace_print+0xd4/0xf0 kernel/stacktrace.c:29 Modules linked in: CPU: 0 UID: 0 PID: 11504 Comm: syz.8.1544 Not tainted syzkaller #0 PREEMPT(none) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:stack_trace_print+0xd4/0xf0 kernel/stacktrace.c:29 Code: fe 33 24 92 89 de ba 20 00 00 00 4c 89 e1 e8 33 13 4d ff 49 83 c6 08 49 ff cd 0f 85 6e ff ff ff eb 0b e8 0f 7f c3 00 eb d4 90 <0f> 0b 90 5b 41 5c 41 5d 41 5e 41 5f 5d e9 0a ff 0d 0f cc 66 0f 1f RSP: 0018:ffff88812e2773d8 EFLAGS: 00010246 RAX: ffff8881149c0b60 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88812e277400 R08: 0000000000000000 R09: 0000000000000000 R10: ffff88812da77418 R11: 0000000000000001 R12: 0000000000000000 R13: 00000000abcd0100 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f9a44a266c0(0000) GS:ffff8881aa691000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000010000 CR3: 000000013f5f4000 CR4: 00000000003526f0 Call Trace: kmsan_print_origin+0xb0/0x340 mm/kmsan/report.c:133 kmsan_report+0x1d3/0x320 mm/kmsan/report.c:196 __msan_warning+0x1b/0x30 mm/kmsan/instrumentation.c:315 bpf_prog_run_generic_xdp+0x1a74/0x1ff0 net/core/dev.c:5305 netif_receive_generic_xdp net/core/dev.c:5388 [inline] do_xdp_generic+0xd52/0x1690 net/core/dev.c:5450 tun_get_user+0x45be/0x6ca0 drivers/net/tun.c:1872 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1996 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] __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746 x64_sys_call+0x3014/0x3e20 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 RIP: 0033:0x7f9a43b8d65f Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48 RSP: 002b:00007f9a44a26000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f9a43dd5fa0 RCX: 00007f9a43b8d65f RDX: 000000000000fdef RSI: 0000200000000300 RDI: 00000000000000c8 RBP: 00007f9a43c11e19 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000fdef R11: 0000000000000293 R12: 0000000000000000 R13: 00007f9a43dd6038 R14: 00007f9a43dd5fa0 R15: 00007ffe1e8b1628 ---[ end trace 0000000000000000 ]--- Uninit was created at: slab_post_alloc_hook mm/slub.c:4197 [inline] slab_alloc_node mm/slub.c:4240 [inline] __do_kmalloc_node mm/slub.c:4375 [inline] __kmalloc_node_track_caller_noprof+0x96d/0x12f0 mm/slub.c:4395 kmalloc_reserve+0x22f/0x4b0 net/core/skbuff.c:600 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:669 alloc_skb include/linux/skbuff.h:1336 [inline] alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6665 sock_alloc_send_pskb+0xad8/0xc70 net/core/sock.c:2958 tun_alloc_skb drivers/net/tun.c:1461 [inline] tun_get_user+0x113f/0x6ca0 drivers/net/tun.c:1794 tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1996 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] __x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746 x64_sys_call+0x3014/0x3e20 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 CPU: 0 UID: 0 PID: 11504 Comm: syz.8.1544 Tainted: G W syzkaller #0 PREEMPT(none) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 =====================================================