------------[ 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.0.17/6250
WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull_reason include/linux/skbuff.h:3294 [inline], CPU#3: syz.0.17/6250
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull_reason include/net/ip_tunnels.h:480 [inline], CPU#3: syz.0.17/6250
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull include/net/ip_tunnels.h:485 [inline], CPU#3: syz.0.17/6250
WARNING: ./include/linux/skbuff.h:2864 at ipgre_xmit+0x8ee/0xbe0 net/ipv4/ip_gre.c:656, CPU#3: syz.0.17/6250
Modules linked in:
CPU: 3 UID: 0 PID: 6250 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:ipgre_xmit+0x8ee/0xbe0 net/ipv4/ip_gre.c:656
Code: 98 df b1 f7 8b 04 24 48 89 df 41 29 c7 43 8d 34 27 e8 e6 33 3e ff 48 85 c0 0f 85 2c f9 ff ff e9 66 fc ff ff e8 73 df b1 f7 90 <0f> 0b 90 e9 91 f8 ff ff e8 65 df b1 f7 48 8d bb cc 00 00 00 48 b8
RSP: 0018:ffffc900016bf7c0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88803fc10500 RCX: 0000000000000200
RDX: ffff888026c72580 RSI: ffffffff8a5a403d RDI: ffff888026c72580
RBP: ffff88802e36a000 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff40 R11: 0000000000000000 R12: 00000000ffffff40
R13: ffff88803fc105b4 R14: ffffffffffffff40 R15: ffff88803fc10500
FS:  00007fe44f7446c0(0000) GS:ffff8880d5e58000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe44ea27dac CR3: 0000000036ae9000 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_sendmsg net/xdp/xsk.c:1390 [inline]
 xsk_sendmsg+0x589/0xa10 net/xdp/xsk.c:1400
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2713
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2767
 __sys_sendmsg+0x160/0x210 net/socket.c:2799
 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: 0033:0x7fe44e79e0d9
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:00007fe44f744028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe44ea25fa0 RCX: 00007fe44e79e0d9
RDX: 0000000000000040 RSI: 0000200000000700 RDI: 0000000000000003
RBP: 00007fe44e835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe44ea26038 R14: 00007fe44ea25fa0 R15: 00007fff65833918
 </TASK>