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BUG: KASAN: slab-out-of-bounds in _decode_session6+0x134a/0x1500 net/ipv6/xfrm6_policy.c:161
Read of size 1 at addr ffff8801b4727c87 by task syz-executor1/16316

CPU: 1 PID: 16316 Comm: syz-executor1 Not tainted 4.20.0-rc1+ #144
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+0x134a/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]
 vti_tunnel_xmit+0x1b1/0x1730 net/ipv4/ip_vti.c:252
 __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_c43b17cda12376d2+0xa38/0x1000

Allocated by task 16316:
 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 mm/slab.c:3722 [inline]
 __kmalloc+0x15b/0x760 mm/slab.c:3731
 kmalloc include/linux/slab.h:551 [inline]
 kzalloc include/linux/slab.h:741 [inline]
 bpf_test_init.isra.10+0x98/0x100 net/bpf/test_run.c:100
 bpf_prog_test_run_skb+0x109/0xcb0 net/bpf/test_run.c:124
 bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1870
 __do_sys_bpf kernel/bpf/syscall.c:2522 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:2466 [inline]
 __x64_sys_bpf+0x3d8/0x520 kernel/bpf/syscall.c:2466
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 15318:
 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
 kernfs_fop_release+0x12b/0x1a0 fs/kernfs/file.c:783
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801b4727a80
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 7 bytes to the right of
 512-byte region [ffff8801b4727a80, ffff8801b4727c80)
The buggy address belongs to the page:
page:ffffea0006d1c9c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0007344e88 ffffea00074f82c8 ffff8801da800940
raw: 0000000000000000 ffff8801b4727080 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801b4727b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801b4727c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801b4727c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801b4727d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801b4727d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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