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BUG: KASAN: slab-out-of-bounds in _decode_session6+0x134e/0x1500 net/ipv6/xfrm6_policy.c:161
Read of size 1 at addr ffff8801be60f707 by task syz-executor0/27269

CPU: 0 PID: 27269 Comm: syz-executor0 Not tainted 4.19.0-rc5+ #106
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+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 _decode_session6+0x134e/0x1500 net/ipv6/xfrm6_policy.c:161
 __xfrm_decode_session+0x71/0x140 net/xfrm/xfrm_policy.c:2299
 xfrm_decode_session include/net/xfrm.h:1232 [inline]
 vti6_tnl_xmit+0x3fc/0x1c0e net/ipv6/ip6_vti.c:542
 __netdev_start_xmit include/linux/netdevice.h:4319 [inline]
 netdev_start_xmit include/linux/netdevice.h:4328 [inline]
 xmit_one net/core/dev.c:3219 [inline]
 dev_hard_start_xmit+0x295/0xc90 net/core/dev.c:3235
 __dev_queue_xmit+0x2f0d/0x3950 net/core/dev.c:3805
 dev_queue_xmit+0x17/0x20 net/core/dev.c:3838
 __bpf_tx_skb net/core/filter.c:2012 [inline]
 __bpf_redirect_common net/core/filter.c:2050 [inline]
 __bpf_redirect+0x5cf/0xb20 net/core/filter.c:2057
 ____bpf_clone_redirect net/core/filter.c:2090 [inline]
 bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2062
 bpf_prog_c39d1ba309a769f7+0x534/0x1000

Allocated by task 27269:
 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:3682 [inline]
 __kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3696
 __kmalloc_reserve.isra.39+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:5126
 __bpf_try_make_writable net/core/filter.c:1633 [inline]
 bpf_try_make_writable net/core/filter.c:1639 [inline]
 bpf_try_make_head_writable net/core/filter.c:1647 [inline]
 ____bpf_clone_redirect net/core/filter.c:2084 [inline]
 bpf_clone_redirect+0x14a/0x490 net/core/filter.c:2062
 bpf_prog_c39d1ba309a769f7+0x534/0x1000

Freed by task 26069:
 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:3813
 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+0x387/0x1c0e net/ipv6/ip6_vti.c:561
 __netdev_start_xmit include/linux/netdevice.h:4319 [inline]
 netdev_start_xmit include/linux/netdevice.h:4328 [inline]
 xmit_one net/core/dev.c:3219 [inline]
 dev_hard_start_xmit+0x295/0xc90 net/core/dev.c:3235
 __dev_queue_xmit+0x2f0d/0x3950 net/core/dev.c:3805
 dev_queue_xmit+0x17/0x20 net/core/dev.c:3838
 __bpf_tx_skb net/core/filter.c:2012 [inline]
 __bpf_redirect_common net/core/filter.c:2050 [inline]
 __bpf_redirect+0x5cf/0xb20 net/core/filter.c:2057
 ____bpf_clone_redirect net/core/filter.c:2090 [inline]
 bpf_clone_redirect+0x2f6/0x490 net/core/filter.c:2062
 0xffffffffa004885e

The buggy address belongs to the object at ffff8801be60f500
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 7 bytes to the right of
 512-byte region [ffff8801be60f500, ffff8801be60f700)
The buggy address belongs to the page:
page:ffffea0006f983c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea000722a908 ffffea000667f888 ffff8801da800940
raw: 0000000000000000 ffff8801be60f000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801be60f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801be60f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801be60f700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801be60f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801be60f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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