KASAN: use-after-free Read in tcp_sk_exit

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    33a0efa4baec devlink: Use DIV_ROUND_UP_ULL in DEVLINK_HEAL..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14e2e55f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=505743eba4e4f68
dashboard link: https://syzkaller.appspot.com/bug?extid=f797267da5e5012d0920
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f797267da5e5012d0920@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in inet_ctl_sock_destroy  
include/net/inet_common.h:56 [inline]
BUG: KASAN: use-after-free in tcp_sk_exit+0x203/0x230  
net/ipv4/tcp_ipv4.c:2588
Read of size 8 at addr ffff888064de4378 by task kworker/u4:3/131

CPU: 0 PID: 131 Comm: kworker/u4:3 Not tainted 5.0.0-rc3+ #17
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: netns cleanup_net
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_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 inet_ctl_sock_destroy include/net/inet_common.h:56 [inline]
 tcp_sk_exit+0x203/0x230 net/ipv4/tcp_ipv4.c:2588
 ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:153
 cleanup_net+0x51d/0xb10 net/core/net_namespace.c:551
 process_one_work+0xd0c/0x1ce0 kernel/workqueue.c:2153
 worker_thread+0x143/0x14a0 kernel/workqueue.c:2296
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 5864:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc mm/kasan/common.c:496 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
 kasan_kmalloc mm/kasan/common.c:504 [inline]
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411
 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3543
 getname_flags fs/namei.c:140 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:129
 getname+0x1a/0x20 fs/namei.c:211
 do_sys_open+0x3a5/0x7c0 fs/open.c:1057
 __do_sys_open fs/open.c:1081 [inline]
 __se_sys_open fs/open.c:1076 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1076
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5864:
 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:458
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
 __cache_free mm/slab.c:3487 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3749
 putname+0xef/0x130 fs/namei.c:261
 do_sys_open+0x3f4/0x7c0 fs/open.c:1072
 __do_sys_open fs/open.c:1081 [inline]
 __se_sys_open fs/open.c:1076 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1076
 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 ffff888064de4180
 which belongs to the cache names_cache of size 4096
The buggy address is located 504 bytes inside of
 4096-byte region [ffff888064de4180, ffff888064de5180)
The buggy address belongs to the page:
page:ffffea0001937900 count:1 mapcount:0 mapping:ffff88821bc45380 index:0x0  
compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0001931108 ffffea0001796b88 ffff88821bc45380
raw: 0000000000000000 ffff888064de4180 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888064de4200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064de4280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff888064de4300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888064de4380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064de4400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with  
syzbot.