------------[ cut here ]------------
len > ((int)(~0U >> 1))
WARNING: ./include/linux/skbuff.h:2864 at pskb_may_pull_reason include/linux/skbuff.h:2864 [inline], CPU#3: syz.0.17/6251
WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull_reason include/linux/skbuff.h:3294 [inline], CPU#3: syz.0.17/6251
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull_reason include/net/ip_tunnels.h:480 [inline], CPU#3: syz.0.17/6251
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull include/net/ip_tunnels.h:485 [inline], CPU#3: syz.0.17/6251
WARNING: ./include/linux/skbuff.h:2864 at gre_tap_xmit+0x61e/0x700 net/ipv4/ip_gre.c:767, CPU#3: syz.0.17/6251
Modules linked in:
CPU: 3 UID: 0 PID: 6251 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:pskb_may_pull_reason include/linux/skbuff.h:2864 [inline]
RIP: 0010:pskb_network_may_pull_reason include/linux/skbuff.h:3294 [inline]
RIP: 0010:pskb_inet_may_pull_reason include/net/ip_tunnels.h:480 [inline]
RIP: 0010:pskb_inet_may_pull include/net/ip_tunnels.h:485 [inline]
RIP: 0010:gre_tap_xmit+0x61e/0x700 net/ipv4/ip_gre.c:767
Code: 5c b2 f7 8b 44 24 04 48 89 df 41 29 c6 41 8d 34 2e e8 d6 3c 3e ff 48 85 c0 0f 85 e3 fb ff ff e9 af fc ff ff e8 33 5c b2 f7 90 <0f> 0b 90 e9 4d fb ff ff e8 e5 96 25 f8 e9 fa fb ff ff e8 0b 97 25
RSP: 0018:ffffc900032ef330 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88803d6ac3c0 RCX: 0000000000000200
RDX: ffff8880329f8000 RSI: ffffffff8a59b9dd RDI: ffff8880329f8000
RBP: 00000000ffffff40 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff40 R11: 0000000000000000 R12: ffff888055fde000
R13: 1ffff9200065de6a R14: ffffffffffffff40 R15: ffff88803d6ac490
FS:  00007f242c0bc6c0(0000) GS:ffff8880d5e5c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001040 CR3: 0000000035d56000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __netdev_start_xmit include/linux/netdevice.h:5429 [inline]
 netdev_start_xmit include/linux/netdevice.h:5438 [inline]
 __dev_direct_xmit+0x5b3/0x750 net/core/dev.c:4990
 __xsk_generic_xmit net/xdp/xsk.c:1280 [inline]
 xsk_generic_xmit+0x2267/0x44a0 net/xdp/xsk.c:1336
 xsk_poll+0x2a5/0x840 net/xdp/xsk.c:1464
 sock_poll+0x160/0x510 net/socket.c:1514
 vfs_poll include/linux/poll.h:82 [inline]
 select_poll_one fs/select.c:480 [inline]
 do_select+0xd54/0x1850 fs/select.c:536
 core_sys_select+0x55b/0xbb0 fs/select.c:677
 do_pselect.constprop.0+0x238/0x270 fs/select.c:770
 __do_sys_pselect6 fs/select.c:809 [inline]
 __se_sys_pselect6 fs/select.c:800 [inline]
 __x64_sys_pselect6+0x149/0x1c0 fs/select.c:800
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f242b19e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f242c0bc028 EFLAGS: 00000246 ORIG_RAX: 000000000000010e
RAX: ffffffffffffffda RBX: 00007f242b425fa0 RCX: 00007f242b19e159
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 0000000000000040
RBP: 00007f242b235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000240 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f242b426038 R14: 00007f242b425fa0 R15: 00007fff86f887d8
 </TASK>