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BUG: KASAN: use-after-free in nla_strlcpy+0x13d/0x150 lib/nlattr.c:314
Read of size 1 at addr ffff8801ba4e945f by task syz-executor6/15176

CPU: 0 PID: 15176 Comm: syz-executor6 Not tainted 4.17.0-rc6+ #57
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:00007f659ca63c68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f659ca646d4 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 6631:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 getname_flags+0xd0/0x5a0 fs/namei.c:140
 user_path_at_empty+0x2d/0x50 fs/namei.c:2555
 do_readlinkat+0x143/0x3e0 fs/stat.c:394
 __do_sys_readlink fs/stat.c:427 [inline]
 __se_sys_readlink fs/stat.c:424 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:424
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6631:
 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]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 putname+0xf2/0x130 fs/namei.c:261
 filename_lookup+0x38b/0x4f0 fs/namei.c:2330
 user_path_at_empty+0x40/0x50 fs/namei.c:2555
 do_readlinkat+0x143/0x3e0 fs/stat.c:394
 __do_sys_readlink fs/stat.c:427 [inline]
 __se_sys_readlink fs/stat.c:424 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:424
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ba4e8480
 which belongs to the cache names_cache of size 4096
The buggy address is located 4063 bytes inside of
 4096-byte region [ffff8801ba4e8480, ffff8801ba4e9480)
The buggy address belongs to the page:
page:ffffea0006e93a00 count:1 mapcount:0 mapping:ffff8801ba4e8480 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801ba4e8480 0000000000000000 0000000100000001
raw: ffffea000729c820 ffffea00063c1720 ffff8801da988dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ba4e9300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801ba4e9380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801ba4e9400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801ba4e9480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801ba4e9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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