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BUG: KASAN: use-after-free in _decode_session6+0xf56/0x1370 net/ipv6/xfrm6_policy.c:137
Read of size 1 at addr ffff888098b6c38d by task syz-executor.5/7205

CPU: 0 PID: 7205 Comm: syz-executor.5 Not tainted 4.19.211-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+0x1fc/0x2ef lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_load1_noabort+0x88/0x90 mm/kasan/report.c:430
 _decode_session6+0xf56/0x1370 net/ipv6/xfrm6_policy.c:137
 __xfrm_decode_session+0x5a/0x130 net/xfrm/xfrm_policy.c:2299
 xfrm_decode_session include/net/xfrm.h:1238 [inline]
 vti_tunnel_xmit+0x279/0x1850 net/ipv4/ip_vti.c:326
 __netdev_start_xmit include/linux/netdevice.h:4349 [inline]
 netdev_start_xmit include/linux/netdevice.h:4363 [inline]
 xmit_one net/core/dev.c:3256 [inline]
 dev_hard_start_xmit+0x1a8/0x920 net/core/dev.c:3272
 sch_direct_xmit+0x2d6/0xf70 net/sched/sch_generic.c:332
 qdisc_restart net/sched/sch_generic.c:395 [inline]
 __qdisc_run+0x4d0/0x1640 net/sched/sch_generic.c:403
 __dev_xmit_skb net/core/dev.c:3500 [inline]
 __dev_queue_xmit+0x1518/0x2e00 net/core/dev.c:3807
 neigh_output include/net/neighbour.h:501 [inline]
 ip6_finish_output2+0x113d/0x2290 net/ipv6/ip6_output.c:120
 ip6_finish_output+0x89b/0x10f0 net/ipv6/ip6_output.c:192
 NF_HOOK_COND include/linux/netfilter.h:278 [inline]
 ip6_output+0x205/0x770 net/ipv6/ip6_output.c:209
 dst_output include/net/dst.h:455 [inline]
 ip6_local_out+0xaf/0x170 net/ipv6/output_core.c:160
 ip6_send_skb+0xb3/0x300 net/ipv6/ip6_output.c:1741
 udp_v6_send_skb+0x7d7/0x1610 net/ipv6/udp.c:1114
 udpv6_sendmsg+0x236b/0x2ae0 net/ipv6/udp.c:1411
 inet_sendmsg+0x132/0x5a0 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xc3/0x120 net/socket.c:661
 sock_write_iter+0x287/0x3c0 net/socket.c:966
 call_write_iter include/linux/fs.h:1821 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x51b/0x770 fs/read_write.c:487
 vfs_write+0x1f3/0x540 fs/read_write.c:549
 ksys_write+0x12b/0x2a0 fs/read_write.c:599
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f1a64228ae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1a6179e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1a6433bf60 RCX: 00007f1a64228ae9
RDX: 0000000000000006 RSI: 0000000020000100 RDI: 0000000000000006
RBP: 00007f1a64282f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffde28e530f R14: 00007f1a6179e300 R15: 0000000000022000

Allocated by task 6064:
 kmem_cache_alloc+0x122/0x370 mm/slab.c:3559
 getname_flags+0xce/0x590 fs/namei.c:140
 do_sys_open+0x26c/0x520 fs/open.c:1079
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6064:
 __cache_free mm/slab.c:3503 [inline]
 kmem_cache_free+0x7f/0x260 mm/slab.c:3765
 putname+0xe1/0x120 fs/namei.c:261
 do_sys_open+0x2ba/0x520 fs/open.c:1094
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888098b6c340
 which belongs to the cache names_cache of size 4096
The buggy address is located 77 bytes inside of
 4096-byte region [ffff888098b6c340, ffff888098b6d340)
The buggy address belongs to the page:
page:ffffea000262db00 count:1 mapcount:0 mapping:ffff88823b843380 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffffea00026c8208 ffffea0002650508 ffff88823b843380
raw: 0000000000000000 ffff888098b6c340 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888098b6c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888098b6c300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888098b6c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888098b6c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888098b6c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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