KASAN: use-after-free Read in __vunmap

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
9cb9c07d6b0c5fd97d83b8ab14d7e308ba4b612f (Fri Feb 23 23:14:17 2018 +0000)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.
user-space arch: i386
CC: [bri...@lists.linux-foundation.org core...@netfilter.org
da...@davemloft.net f...@strlen.de kad...@blackhole.kfki.hu
linux-...@vger.kernel.org net...@vger.kernel.org
netfilt...@vger.kernel.org pa...@netfilter.org
ste...@networkplumber.org]

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==================================================================
BUG: KASAN: use-after-free in __vunmap+0x322/0x380 mm/vmalloc.c:1535
Read of size 8 at addr ffff8801c1e6b110 by task syz-executor5/7980

CPU: 1 PID: 7980 Comm: syz-executor5 Not tainted 4.16.0-rc2+ #237
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report+0x23b/0x360 mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
__vunmap+0x322/0x380 mm/vmalloc.c:1535
vfree+0x50/0xe0 mm/vmalloc.c:1606
do_replace_finish+0x1c41/0x2620 net/bridge/netfilter/ebtables.c:1062
compat_do_replace+0x5e5/0x7c0 net/bridge/netfilter/ebtables.c:2289
compat_do_ebt_set_ctl+0x22a/0x2d0 net/bridge/netfilter/ebtables.c:2330
compat_nf_sockopt net/netfilter/nf_sockopt.c:144 [inline]
compat_nf_setsockopt+0x88/0x130 net/netfilter/nf_sockopt.c:156
compat_ip_setsockopt+0x8b/0xd0 net/ipv4/ip_sockglue.c:1285
inet_csk_compat_setsockopt+0x95/0x120 net/ipv4/inet_connection_sock.c:1041
compat_tcp_setsockopt+0x3d/0x70 net/ipv4/tcp.c:2916
compat_sock_common_setsockopt+0xb2/0x140 net/core/sock.c:2986
C_SYSC_setsockopt net/compat.c:403 [inline]
compat_SyS_setsockopt net/compat.c:386 [inline]
C_SYSC_socketcall net/compat.c:853 [inline]
compat_SyS_socketcall+0xbf7/0x17c0 net/compat.c:788
do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fcbc99
RSP: 002b:000000000844eb30 EFLAGS: 00000202 ORIG_RAX: 0000000000000066
RAX: ffffffffffffffda RBX: 000000000000000e RCX: 000000000844eb4c
RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000000000000000e
RBP: 0000000000000020 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 15727:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
kmem_cache_alloc_trace+0x136/0x740 mm/slab.c:3607
kmalloc include/linux/slab.h:512 [inline]
kzalloc include/linux/slab.h:701 [inline]
netlbl_secattr_alloc include/net/netlabel.h:396 [inline]
selinux_netlbl_sock_genattr+0xb6/0x3d0 security/selinux/netlabel.c:90
selinux_netlbl_socket_post_create+0x6a/0x140
security/selinux/netlabel.c:340
selinux_socket_post_create+0x356/0x970 security/selinux/hooks.c:4399
security_socket_post_create+0x8b/0xc0 security/security.c:1344
__sock_create+0x6a4/0x850 net/socket.c:1301
sock_create net/socket.c:1325 [inline]
SYSC_socket net/socket.c:1355 [inline]
SyS_socket+0xeb/0x1d0 net/socket.c:1335
C_SYSC_socketcall net/compat.c:813 [inline]
compat_SyS_socketcall+0x4cc/0x17c0 net/compat.c:788
do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 15727:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
__cache_free mm/slab.c:3485 [inline]
kfree+0xd9/0x260 mm/slab.c:3800
netlbl_secattr_free include/net/netlabel.h:410 [inline]
selinux_netlbl_sk_security_free+0x104/0x2f0 security/selinux/netlabel.c:170
selinux_sk_free_security+0x47/0x60 security/selinux/hooks.c:4907
security_sk_free+0x48/0x80 security/security.c:1431
sk_prot_free net/core/sock.c:1504 [inline]
__sk_destruct+0x60f/0x920 net/core/sock.c:1590
sk_destruct+0x47/0x80 net/core/sock.c:1598
__sk_free+0xf1/0x2b0 net/core/sock.c:1609
sk_free+0x2a/0x40 net/core/sock.c:1620
sock_put include/net/sock.h:1658 [inline]
tcp_close+0x966/0x1190 net/ipv4/tcp.c:2346
inet_release+0xed/0x1c0 net/ipv4/af_inet.c:427
sock_release+0x8d/0x1e0 net/socket.c:595
sock_close+0x16/0x20 net/socket.c:1149
__fput+0x327/0x7e0 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x275/0x2f0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
do_syscall_32_irqs_on arch/x86/entry/common.c:336 [inline]
do_fast_syscall_32+0xbe6/0xf9f arch/x86/entry/common.c:392
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

The buggy address belongs to the object at ffff8801c1e6b100
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 16 bytes inside of
64-byte region [ffff8801c1e6b100, ffff8801c1e6b140)
The buggy address belongs to the page:
page:ffffea0007079ac0 count:1 mapcount:0 mapping:ffff8801c1e6b000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c1e6b000 0000000000000000 0000000100000020
raw: ffffea0007194fe0 ffffea00068c6b20 ffff8801dac00340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801c1e6b000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8801c1e6b080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff8801c1e6b100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff8801c1e6b180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8801c1e6b200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.