skbuff: skb_under_panic: text:00000000d8c6bef3 len:31 put:24 head:00000000ef28dcdd data:00000000dbada750 tail:0x7 end:0xc0 dev:gre0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:104!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3664 Comm: syzkaller186644 Not tainted 4.15.0-rc8+ #173
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_panic+0x162/0x1f0 net/core/skbuff.c:100
RSP: 0018:ffff8801d9ab76b0 EFLAGS: 00010282
RAX: 0000000000000083 RBX: ffff8801d4d811c0 RCX: 0000000000000000
RDX: 0000000000000083 RSI: 1ffff1003b356e96 RDI: ffffed003b356eca
RBP: ffff8801d9ab7718 R08: 1ffff1003b356e58 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff861f8fe0
R13: ffffffff84a31e3d R14: 0000000000000018 R15: ffff8801d31d00c0
FS:  0000000000000000(0000) GS:ffff8801db200000(0063) knlGS:0000000008ed6840
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000208bc000 CR3: 00000001bc95d003 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 skb_under_panic net/core/skbuff.c:114 [inline]
 skb_push+0xce/0xf0 net/core/skbuff.c:1714
 ipgre_header+0x6d/0x4e0 net/ipv4/ip_gre.c:877
 dev_hard_header include/linux/netdevice.h:2721 [inline]
 pppoe_sendmsg+0x58e/0x8b0 drivers/net/ppp/pppoe.c:890
 sock_sendmsg_nosec net/socket.c:638 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:648
 sock_write_iter+0x31a/0x5d0 net/socket.c:917
 call_write_iter include/linux/fs.h:1772 [inline]
 do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653
 do_iter_write+0x154/0x540 fs/read_write.c:932
 compat_writev+0x225/0x420 fs/read_write.c:1246
 do_compat_writev+0x115/0x220 fs/read_write.c:1267
 C_SYSC_writev fs/read_write.c:1278 [inline]
 compat_SyS_writev+0x26/0x30 fs/read_write.c:1274
 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
 do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
RIP: 0023:0xf7f9ac79
RSP: 002b:00000000ffefbccc EFLAGS: 00000286 ORIG_RAX: 0000000000000092
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020211f90
RDX: 0000000000000001 RSI: 00000000ffefbd2c RDI: 0000000000000003
RBP: 00000000ffefbdbc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 04 01 84 c0 74 04 3c 03 7e 23 8b 8b 80 00 00 00 41 57 48 c7 c7 a0 88 1f 86 52 56 4c 89 ea 41 50 4c 89 e6 45 89 f0 e8 b6 bd 28 fd <0f> 0b 4c 89 4d b8 4c 89 45 c0 48 89 75 c8 48 89 55 d0 e8 f7 09 
RIP: skb_panic+0x162/0x1f0 net/core/skbuff.c:100 RSP: ffff8801d9ab76b0
---[ end trace bd8c65a61baea614 ]---