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BUG: KASAN: use-after-free in _decode_session6+0x149b/0x1500 net/ipv6/xfrm6_policy.c:190
Read of size 1 at addr ffff8801c6f8c516 by task syz-executor1/19429

CPU: 0 PID: 19429 Comm: syz-executor1 Not tainted 4.20.0-rc1+ #141
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
 _decode_session6+0x149b/0x1500 net/ipv6/xfrm6_policy.c:190
 __xfrm_decode_session+0x71/0x140 net/xfrm/xfrm_policy.c:2299
 xfrm_decode_session include/net/xfrm.h:1232 [inline]
 vti6_tnl_xmit+0x3fc/0x1c10 net/ipv6/ip6_vti.c:542
 __netdev_start_xmit include/linux/netdevice.h:4344 [inline]
 netdev_start_xmit include/linux/netdevice.h:4353 [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_c39d1ba309a769f7+0x26c/0x1000

Allocated by task 18257:
 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_c39d1ba309a769f7+0x460/0x1000

Freed by task 18257:
 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]
 kfree_skb+0x1bb/0x580 net/core/skbuff.c:659
 vti6_tnl_xmit+0x387/0x1c10 net/ipv6/ip6_vti.c:561
 __netdev_start_xmit include/linux/netdevice.h:4344 [inline]
 netdev_start_xmit include/linux/netdevice.h:4353 [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_c39d1ba309a769f7+0x460/0x1000

The buggy address belongs to the object at ffff8801c6f8c500
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 22 bytes inside of
 512-byte region [ffff8801c6f8c500, ffff8801c6f8c700)
The buggy address belongs to the page:
page:ffffea00071be300 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0007455048 ffffea0006e970c8 ffff8801da800940
raw: 0000000000000000 ffff8801c6f8c000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c6f8c400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c6f8c480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801c6f8c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8801c6f8c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801c6f8c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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