KASAN: slab-out-of-bounds Read in tcp_sk_exit

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    e15aa3b2b138 ucc_geth: Reset BQL queue when stopping device
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=149b240f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4fceea9e2d99ac20
dashboard link: https://syzkaller.appspot.com/bug?extid=dfc9db054bca3a83f4a0
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+dfc9db054bca3a83f4a0@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in inet_ctl_sock_destroy  
include/net/inet_common.h:56 [inline]
BUG: KASAN: slab-out-of-bounds in tcp_sk_exit+0x203/0x230  
net/ipv4/tcp_ipv4.c:2588
Read of size 8 at addr ffff88808a260bac by task kworker/u4:4/2564

CPU: 0 PID: 2564 Comm: kworker/u4:4 Not tainted 5.0.0-rc4+ #53
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 8016:
 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
 user_path_at_empty+0x2f/0x50 fs/namei.c:2608
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x129/0x210 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3175 [inline]
 __do_sys_newlstat+0xa4/0x130 fs/stat.c:352
 __se_sys_newlstat fs/stat.c:346 [inline]
 __x64_sys_newlstat+0x54/0x80 fs/stat.c:346
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8016:
 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
 filename_lookup+0x359/0x530 fs/namei.c:2357
 user_path_at_empty+0x43/0x50 fs/namei.c:2608
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x129/0x210 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3175 [inline]
 __do_sys_newlstat+0xa4/0x130 fs/stat.c:352
 __se_sys_newlstat fs/stat.c:346 [inline]
 __x64_sys_newlstat+0x54/0x80 fs/stat.c:346
 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 ffff88808a260e80
 which belongs to the cache names_cache of size 4096
The buggy address is located 724 bytes to the left of
 4096-byte region [ffff88808a260e80, ffff88808a261e80)
The buggy address belongs to the page:
page:ffffea0002289800 count:1 mapcount:0 mapping:ffff88821bc45380 index:0x0  
compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002289888 ffffea000257cf88 ffff88821bc45380
raw: 0000000000000000 ffff88808a260e80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808a260a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808a260b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88808a260b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                  ^
 ffff88808a260c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808a260c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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