==================================================================
BUG: KASAN: slab-out-of-bounds in ip6_tnl_parse_tlv_enc_lim+0x5df/0x660 net/ipv6/ip6_tunnel.c:417
Read of size 1 at addr ffff8801d8f4ba47 by task syz-executor4/24106

CPU: 1 PID: 24106 Comm: syz-executor4 Not tainted 4.20.0-rc1+ #108
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 ip6_tnl_parse_tlv_enc_lim+0x5df/0x660 net/ipv6/ip6_tunnel.c:417
 ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1348 [inline]
 ip6_tnl_start_xmit+0x49f/0x25a0 net/ipv6/ip6_tunnel.c:1412
 __netdev_start_xmit include/linux/netdevice.h:4356 [inline]
 netdev_start_xmit include/linux/netdevice.h:4365 [inline]
 xmit_one net/core/dev.c:3252 [inline]
 dev_hard_start_xmit+0x295/0xc80 net/core/dev.c:3268
 __dev_queue_xmit+0x2f71/0x3ad0 net/core/dev.c:3838
 dev_queue_xmit+0x17/0x20 net/core/dev.c:3871
 __bpf_tx_skb net/core/filter.c:2017 [inline]
 __bpf_redirect_common net/core/filter.c:2055 [inline]
 __bpf_redirect+0x5cf/0xb20 net/core/filter.c:2062
 ____bpf_clone_redirect net/core/filter.c:2095 [inline]
 bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2067
 bpf_prog_759a992c578a3894+0xf55/0x1000

Allocated by task 24106:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc_node mm/slab.c:3684 [inline]
 __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3698
 __kmalloc_reserve.isra.40+0x41/0xe0 net/core/skbuff.c:137
 pskb_expand_head+0x230/0x10f0 net/core/skbuff.c:1460
 skb_ensure_writable+0x3dd/0x640 net/core/skbuff.c:5073
 __bpf_try_make_writable net/core/filter.c:1638 [inline]
 bpf_try_make_writable net/core/filter.c:1644 [inline]
 bpf_try_make_head_writable net/core/filter.c:1652 [inline]
 ____bpf_clone_redirect net/core/filter.c:2089 [inline]
 bpf_clone_redirect+0x14a/0x490 net/core/filter.c:2067
 bpf_prog_759a992c578a3894+0xf55/0x1000

Freed by task 22834:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xcf/0x230 mm/slab.c:3817
 skb_free_head+0x99/0xc0 net/core/skbuff.c:550
 skb_release_data+0x6a4/0x880 net/core/skbuff.c:570
 skb_release_all+0x4a/0x60 net/core/skbuff.c:627
 __kfree_skb net/core/skbuff.c:641 [inline]
 consume_skb+0x1ae/0x570 net/core/skbuff.c:701
 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
 netlink_unicast+0x5ad/0x760 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:631
 ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
 __sys_sendmsg+0x11d/0x280 net/socket.c:2154
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg net/socket.c:2161 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d8f4b840
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 7 bytes to the right of
 512-byte region [ffff8801d8f4b840, ffff8801d8f4ba40)
The buggy address belongs to the page:
page:ffffea000763d2c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0006f2d948 ffffea0006f2fb48 ffff8801da800940
raw: 0000000000000000 ffff8801d8f4b0c0 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d8f4b900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d8f4b980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801d8f4ba00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                           ^
 ffff8801d8f4ba80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801d8f4bb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================