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BUG: KASAN: use-after-free in __xfrm6_tunnel_spi_lookup+0x3a9/0x3b0 net/ipv6/xfrm6_tunnel.c:79
Read of size 8 at addr ffff888093b56228 by task syz-executor.1/10534
CPU: 0 PID: 10534 Comm: syz-executor.1 Not tainted 5.8.0-rc5-next-20200716-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 __xfrm6_tunnel_spi_lookup+0x3a9/0x3b0 net/ipv6/xfrm6_tunnel.c:79
 xfrm6_tunnel_spi_lookup+0x8a/0x1d0 net/ipv6/xfrm6_tunnel.c:95
 xfrmi6_rcv_tunnel+0xb9/0x100 net/xfrm/xfrm_interface.c:824
 tunnel46_rcv+0xef/0x2b0 net/ipv6/tunnel6.c:193
 ip6_protocol_deliver_rcu+0x2e8/0x1670 net/ipv6/ip6_input.c:433
 ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
 dst_input include/net/dst.h:449 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
 netif_receive_skb_internal net/core/dev.c:5503 [inline]
 netif_receive_skb+0x159/0x990 net/core/dev.c:5562
 tun_rx_batched.isra.0+0x460/0x720 drivers/net/tun.c:1518
 tun_get_user+0x23b2/0x35b0 drivers/net/tun.c:1972
 tun_chr_write_iter+0xba/0x151 drivers/net/tun.c:2001
 call_write_iter include/linux/fs.h:1879 [inline]
 new_sync_write+0x422/0x650 fs/read_write.c:515
 vfs_write+0x5c6/0x6f0 fs/read_write.c:595
 ksys_write+0x12d/0x250 fs/read_write.c:648
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x415c91
Code: Bad RIP value.
RSP: 002b:00007f4c9ba62c60 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000078bf00 RCX: 0000000000415c91
RDX: 000000000000004a RSI: 0000000020000280 RDI: 00000000000000f0
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f4c9ba639d0 R11: 0000000000000293 R12: 000000000078bf0c
R13: 00007fff97a0c88f R14: 00007f4c9ba639c0 R15: 000000000078bf0c
Allocated by task 204:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 slab_post_alloc_hook mm/slab.h:535 [inline]
 slab_alloc mm/slab.c:3312 [inline]
 kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482
 copy_fs_struct+0x43/0x2f0 fs/fs_struct.c:114
 copy_fs kernel/fork.c:1436 [inline]
 copy_process+0x49c6/0x6b70 kernel/fork.c:2067
 _do_fork+0xe8/0xb10 kernel/fork.c:2434
 kernel_thread+0xb5/0xf0 kernel/fork.c:2486
 call_usermodehelper_exec_work kernel/umh.c:184 [inline]
 call_usermodehelper_exec_work+0x16d/0x260 kernel/umh.c:170
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Freed by task 10461:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3418 [inline]
 kmem_cache_free.part.0+0x67/0x1f0 mm/slab.c:3693
 free_fs_struct fs/fs_struct.c:92 [inline]
 exit_fs+0x123/0x170 fs/fs_struct.c:108
 do_exit+0xb4b/0x29f0 kernel/exit.c:802
 call_usermodehelper_exec_async+0x3b5/0x4f0 kernel/umh.c:114
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
The buggy address belongs to the object at ffff888093b56200
 which belongs to the cache fs_cache of size 160
The buggy address is located 40 bytes inside of
 160-byte region [ffff888093b56200, ffff888093b562a0)
The buggy address belongs to the page:
page:00000000b00af598 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888093b56100 pfn:0x93b56
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000251dc48 ffffea0002a1f208 ffff8880aa02f700
raw: ffff888093b56100 ffff888093b56000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
 ffff888093b56100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888093b56180: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888093b56200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888093b56280: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888093b56300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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