------------[ cut here ]------------
len > ((int)(~0U >> 1))
WARNING: ./include/linux/skbuff.h:2864 at pskb_may_pull_reason include/linux/skbuff.h:2864 [inline], CPU#2: syz.0.17/5906
WARNING: ./include/linux/skbuff.h:2864 at pskb_network_may_pull_reason include/linux/skbuff.h:3289 [inline], CPU#2: syz.0.17/5906
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull_reason include/net/ip_tunnels.h:480 [inline], CPU#2: syz.0.17/5906
WARNING: ./include/linux/skbuff.h:2864 at pskb_inet_may_pull include/net/ip_tunnels.h:485 [inline], CPU#2: syz.0.17/5906
WARNING: ./include/linux/skbuff.h:2864 at ip6gre_tunnel_xmit+0x547/0xe60 net/ipv6/ip6_gre.c:885, CPU#2: syz.0.17/5906
Modules linked in:
CPU: 2 UID: 0 PID: 5906 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:3289 [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:ip6gre_tunnel_xmit+0x547/0xe60 net/ipv6/ip6_gre.c:885
Code: ff ff e8 6c 91 72 f7 41 0f b7 f4 31 d2 48 89 df e8 2e ea fb fe 41 89 c4 0f b7 c0 48 89 04 24 e9 9b fe ff ff e8 4a 91 72 f7 90 <0f> 0b 90 e9 4d fc ff ff e8 3c 91 72 f7 8b 34 24 44 89 e7 e8 e1 8a
RSP: 0018:ffffc90003b6f498 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88803971fe00 RCX: 0000000000000200
RDX: ffff88802b602580 RSI: ffffffff8a9945e6 RDI: ffff88802b602580
RBP: ffff888037c60000 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff40 R11: 0000000000000000 R12: 00000000ffffff40
R13: 1ffff9200076de98 R14: ffff88803971feb4 R15: ffffffffffffff40
FS:  000055556ec4e500(0000) GS:ffff8880d5d64000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f33bff892c0 CR3: 0000000027be2000 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]
 do_pollfd fs/select.c:877 [inline]
 do_poll fs/select.c:920 [inline]
 do_sys_poll+0x6e5/0xe90 fs/select.c:1015
 __do_sys_ppoll fs/select.c:1112 [inline]
 __se_sys_ppoll fs/select.c:1092 [inline]
 __x64_sys_ppoll+0x2b5/0x350 fs/select.c:1092
 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: 0033:0x7f33bff9e159
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:00007fff3659f938 EFLAGS: 00000246 ORIG_RAX: 000000000000010f
RAX: ffffffffffffffda RBX: 00007f33c0225fa0 RCX: 00007f33bff9e159
RDX: 0000000000000000 RSI: 20000000000000dc RDI: 00002000000000c0
RBP: 00007f33c0035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f33c0225fac R14: 00007f33c0225fa0 R15: 00007f33c0225fa0
 </TASK>