==================================================================
BUG: KASAN: wild-memory-access in memcpy include/linux/string.h:339 [inline]
BUG: KASAN: wild-memory-access in skb_copy_ubufs+0xc51/0x1940 net/core/skbuff.c:1229
Read of size 4096 at addr 5701f68990f93157 by task syz-executor4/4396

CPU: 3 PID: 4396 Comm: syz-executor4 Not tainted 4.13.0-rc5-next-20170816+ #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 kasan_report_error mm/kasan/report.c:349 [inline]
 kasan_report+0x12e/0x340 mm/kasan/report.c:409
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:339 [inline]
 skb_copy_ubufs+0xc51/0x1940 net/core/skbuff.c:1229
 skb_orphan_frags_rx include/linux/skbuff.h:2548 [inline]
 __netif_receive_skb_core+0x2084/0x33d0 net/core/dev.c:4415
 __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:00007f49e1691c00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000004c RCX: 000000000040bab1
RDX: 000000000000004c RSI: 0000000020d96000 RDI: 0000000000000015
RBP: 0000000000a5f870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f49e16929c0 R15: 00007f49e1692700
==================================================================
Kernel panic - not syncing: panic_on_warn set ...

CPU: 3 PID: 4396 Comm: syz-executor4 Tainted: G    B           4.13.0-rc5-next-20170816+ #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x417 kernel/panic.c:180
 kasan_end_report+0x50/0x50 mm/kasan/report.c:176
 kasan_report_error mm/kasan/report.c:356 [inline]
 kasan_report+0x137/0x340 mm/kasan/report.c:409
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:339 [inline]
 skb_copy_ubufs+0xc51/0x1940 net/core/skbuff.c:1229
 skb_orphan_frags_rx include/linux/skbuff.h:2548 [inline]
 __netif_receive_skb_core+0x2084/0x33d0 net/core/dev.c:4415
 __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:00007f49e1691c00 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000004c RCX: 000000000040bab1
RDX: 000000000000004c RSI: 0000000020d96000 RDI: 0000000000000015
RBP: 0000000000a5f870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f49e16929c0 R15: 00007f49e1692700
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..