syzbot

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BUG: KASAN: use-after-free in xfrm_policy_insert_inexact_list net/xfrm/xfrm_policy.c:1497 [inline]
BUG: KASAN: use-after-free in xfrm_policy_inexact_insert+0xbfa/0xda0 net/xfrm/xfrm_policy.c:1202
Read of size 1 at addr ffff88802c5798d9 by task syz-executor4/30533

CPU: 1 PID: 30533 Comm: syz-executor4 Not tainted 4.20.0+ #19
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+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 xfrm_policy_insert_inexact_list net/xfrm/xfrm_policy.c:1497 [inline]
 xfrm_policy_inexact_insert+0xbfa/0xda0 net/xfrm/xfrm_policy.c:1202
 xfrm_policy_insert+0x623/0x910 net/xfrm/xfrm_policy.c:1570
 xfrm_add_policy+0x2a1/0x6c0 net/xfrm/xfrm_user.c:1657
 xfrm_user_rcv_msg+0x458/0x8d0 net/xfrm/xfrm_user.c:2663
 netlink_rcv_skb+0x17d/0x410 net/netlink/af_netlink.c:2477
 xfrm_netlink_rcv+0x70/0x90 net/xfrm/xfrm_user.c:2671
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x574/0x770 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0xa05/0xf90 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 ___sys_sendmsg+0x7ec/0x910 net/socket.c:2116
 __sys_sendmsg+0x112/0x270 net/socket.c:2154
 __do_sys_sendmsg net/socket.c:2163 [inline]
 __se_sys_sendmsg net/socket.c:2161 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f3d823d1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457ec9
RDX: 0000000000000000 RSI: 0000000020000d40 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3d823d26d4
R13: 00000000004c544b R14: 00000000004d9098 R15: 00000000ffffffff

Allocated by task 28350:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc mm/kasan/common.c:482 [inline]
 kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397
 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3541
 getname_flags fs/namei.c:140 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:129
 getname fs/namei.c:211 [inline]
 user_path_mountpoint_at+0x29/0x50 fs/namei.c:2747
 ksys_umount+0x198/0x1340 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 28350:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3747
 putname+0xef/0x130 fs/namei.c:261
 filename_mountpoint+0x337/0x490 fs/namei.c:2725
 user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2747
 ksys_umount+0x198/0x1340 fs/namespace.c:1645
 __do_sys_umount fs/namespace.c:1671 [inline]
 __se_sys_umount fs/namespace.c:1669 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1669
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88802c578a80
 which belongs to the cache names_cache of size 4096
The buggy address is located 3673 bytes inside of
 4096-byte region [ffff88802c578a80, ffff88802c579a80)
The buggy address belongs to the page:
page:ffffea0000b15e00 count:1 mapcount:0 mapping:ffff88821bc49080 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea00016e6a08 ffffea00015dc488 ffff88821bc49080
raw: 0000000000000000 ffff88802c578a80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88802c579780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802c579800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802c579880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88802c579900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802c579980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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