------------[ cut here ]------------
WARNING: CPU: 1 PID: 5900 at net/core/dev.c:6715 napi_hash_add net/core/dev.c:6661 [inline]
WARNING: CPU: 1 PID: 5900 at net/core/dev.c:6715 netif_napi_add+0x630/0x8b0 net/core/dev.c:6738
Modules linked in:
CPU: 1 PID: 5900 Comm: syz-executor.0 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:netif_napi_add+0x630/0x8b0 net/core/dev.c:6715
Code: 5b 5d 41 5c 41 5d 41 5e 41 5f e9 4b 5f d4 01 c7 05 31 55 7a 05 09 00 00 00 41 bf 09 00 00 00 41 be 09 00 00 00 e9 66 fe ff ff <0f> 0b e9 1a fe ff ff e8 04 bc 43 fb e9 c3 fe ff ff e8 ea bb 43 fb
RSP: 0018:ffffc9000189fc68 EFLAGS: 00010247
RAX: 0000000000000001 RBX: ffff88801ce30000 RCX: ffffffff865d323b
RDX: ffffed1004b3e8b6 RSI: 0000000000000008 RDI: ffff8880259f45a8
RBP: ffff8880259f45a8 R08: 0000000000000001 R09: ffff8880259f45af
R10: ffffed1004b3e8b5 R11: 0000000000000001 R12: 0000000000000000
R13: ffff8880259f4598 R14: 0000000000000040 R15: ffffffff84489ea0
FS:  00007f14c2ff1700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffe78fc058 CR3: 00000000151f3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 netif_tx_napi_add include/linux/netdevice.h:2380 [inline]
 tun_napi_init drivers/net/tun.c:257 [inline]
 tun_attach.isra.0+0x92d/0x1490 drivers/net/tun.c:799
 __tun_chr_ioctl.isra.0+0x24c4/0x3c20 drivers/net/tun.c:2736
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x11f/0x190 fs/ioctl.c:739
 do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f14c389d109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f14c2ff1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f14c39b0030 RCX: 00007f14c389d109
RDX: 0000000020000200 RSI: 00000000400454ca RDI: 0000000000000003
RBP: 00007f14c38f705d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea3921c6f R14: 00007f14c2ff1300 R15: 0000000000022000