kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3038 Comm: syz-executor0 Not tainted 4.13.0-rc5-next-20170815+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006c7fc340 task.stack: ffff880069728000
RIP: 0010:__read_once_size include/linux/compiler.h:276 [inline]
RIP: 0010:compound_head include/linux/page-flags.h:146 [inline]
RIP: 0010:put_page include/linux/mm.h:811 [inline]
RIP: 0010:__skb_frag_unref include/linux/skbuff.h:2743 [inline]
RIP: 0010:skb_release_data+0x26c/0x790 net/core/skbuff.c:568
RSP: 0018:ffff88006972eda8 EFLAGS: 00010207
RAX: 0e824260409bede2 RBX: dffffc0000000000 RCX: 1ffff1000d2e5de4
RDX: 0000000000000000 RSI: 1ffff100076c44e7 RDI: 7412130204df6f15
RBP: ffff88006972eec8 R08: ffff88003b622788 R09: 0000000000000000
R10: ffff88006972f6b0 R11: 0000000000000007 R12: ffff8800388a01b0
R13: ffffed000d2e5dcc R14: 1ffff1000d2e5dc4 R15: 7412130204df6ef5
FS:  00007f8e80a85700(0000) GS:ffff88003ed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000457040 CR3: 000000003b6bb000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 skb_release_all+0x4a/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 kfree_skb+0x15d/0x4c0 net/core/skbuff.c:663
 ip_rcv+0x40a/0x17d0 net/ipv4/ip_input.c:497
 __netif_receive_skb_core+0x19af/0x33d0 net/core/dev.c:4418
 __netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4456
 netif_receive_skb_internal+0x10b/0x5e0 net/core/dev.c:4527
 netif_receive_skb+0xae/0x390 net/core/dev.c:4551
 tun_rx_batched.isra.43+0x5e7/0x860 drivers/net/tun.c:1221
 tun_get_user+0x11dd/0x2150 drivers/net/tun.c:1542
 tun_chr_write_iter+0xd8/0x190 drivers/net/tun.c:1568
 call_write_iter include/linux/fs.h:1742 [inline]
 new_sync_write fs/read_write.c:457 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:470
 vfs_write+0x189/0x510 fs/read_write.c:518
 SYSC_write fs/read_write.c:565 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:557
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x40bab1
RSP: 002b:00007f8e80a84c00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000003a RCX: 000000000040bab1
RDX: 000000000000003a RSI: 0000000020d96000 RDI: 0000000000000003
RBP: 0000000000a5f870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8e80a859c0 R15: 00007f8e80a85700
Code: c6 e8 c9 78 8d fd 4c 89 e0 48 c1 e8 03 80 3c 18 00 0f 85 93 04 00 00 4d 8b 3c 24 41 c6 45 00 00 49 8d 7f 20 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 6b 04 00 00 41 80 7d 00 00 49 8b 47 20 0f 85 
RIP: __read_once_size include/linux/compiler.h:276 [inline] RSP: ffff88006972eda8
RIP: compound_head include/linux/page-flags.h:146 [inline] RSP: ffff88006972eda8
RIP: put_page include/linux/mm.h:811 [inline] RSP: ffff88006972eda8
RIP: __skb_frag_unref include/linux/skbuff.h:2743 [inline] RSP: ffff88006972eda8
RIP: skb_release_data+0x26c/0x790 net/core/skbuff.c:568 RSP: ffff88006972eda8
---[ end trace 055286025edfdd34 ]---