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BUG: KASAN: use-after-free in nla_strlcpy+0x13d/0x150 lib/nlattr.c:314
Read of size 1 at addr ffff8801d3d14d5a by task syz-executor2/7910

CPU: 1 PID: 7910 Comm: syz-executor2 Not tainted 4.17.0-rc7+ #71
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 nla_strlcpy+0x13d/0x150 lib/nlattr.c:314
 nfnl_acct_new+0x574/0xc50 net/netfilter/nfnetlink_acct.c:118
 nfnetlink_rcv_msg+0xdb5/0xff0 net/netfilter/nfnetlink.c:212
 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2448
 nfnetlink_rcv+0x1fe/0x1ba0 net/netfilter/nfnetlink.c:513
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x58b/0x740 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0x9f0/0xfa0 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:639
 ___sys_sendmsg+0x805/0x940 net/socket.c:2117
 __sys_sendmsg+0x115/0x270 net/socket.c:2155
 __do_sys_sendmsg net/socket.c:2164 [inline]
 __se_sys_sendmsg net/socket.c:2162 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2162
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a09
RSP: 002b:00007fe71123bc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe71123c6d4 RCX: 0000000000455a09
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000005a3 R14: 00000000006fc7e8 R15: 0000000000000000

Allocated by task 6730:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc_track_caller+0x14a/0x760 mm/slab.c:3733
 kstrdup+0x39/0x70 mm/util.c:56
 kstrdup_const+0x66/0x80 mm/util.c:77
 alloc_vfsmnt+0x1b3/0x9d0 fs/namespace.c:214
 clone_mnt+0x11c/0x1480 fs/namespace.c:1077
 copy_tree+0x46c/0xae0 fs/namespace.c:1806
 propagate_one+0x4db/0x910 fs/pnode.c:265
 propagate_mnt+0x18a/0x3e0 fs/pnode.c:315
 attach_recursive_mnt+0x5f8/0xb50 fs/namespace.c:2033
 graft_tree+0x1aa/0x240 fs/namespace.c:2133
 do_loopback fs/namespace.c:2254 [inline]
 do_mount+0x2745/0x3070 fs/namespace.c:2842
 ksys_mount+0x12d/0x140 fs/namespace.c:3064
 __do_sys_mount fs/namespace.c:3078 [inline]
 __se_sys_mount fs/namespace.c:3075 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 kfree_const+0x59/0x70 mm/util.c:38
 free_vfsmnt+0x37/0x80 fs/namespace.c:640
 delayed_free_vfsmnt+0x16/0x20 fs/namespace.c:649
 __rcu_reclaim kernel/rcu/rcu.h:178 [inline]
 rcu_do_batch kernel/rcu/tree.c:2675 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline]
 rcu_process_callbacks+0x941/0x15f0 kernel/rcu/tree.c:2914
 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801d3d14d40
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 26 bytes inside of
 32-byte region [ffff8801d3d14d40, ffff8801d3d14d60)
The buggy address belongs to the page:
page:ffffea00074f4500 count:1 mapcount:0 mapping:ffff8801d3d14000 index:0xffff8801d3d14fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d3d14000 ffff8801d3d14fc1 0000000100000031
raw: ffffea00073e16a0 ffffea00074bce60 ffff8801da8001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d3d14c00: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff8801d3d14c80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801d3d14d00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                                                    ^
 ffff8801d3d14d80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d3d14e00: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
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