KASAN: use-after-free Write in xt_rateest_tg_checkentry

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
868c36dcc949c26bc74fa4661b670d9acc6489e4 (Mon Jan 29 03:00:16 2018 +0000)
Merge tag 'wireless-drivers-next-for-davem-2018-01-26' of
git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers-next

C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: syzbot+5cb189...@syzkaller.appspotmail.com
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==================================================================
BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:674
[inline]
BUG: KASAN: use-after-free in xt_rateest_hash_insert
net/netfilter/xt_RATEEST.c:39 [inline]
BUG: KASAN: use-after-free in xt_rateest_tg_checkentry+0xa01/0xaa0
net/netfilter/xt_RATEEST.c:141
Write of size 8 at addr ffff8801afbcc258 by task syzkaller409551/4159

CPU: 0 PID: 4159 Comm: syzkaller409551 Not tainted 4.15.0-rc9+ #214
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+0x194/0x257 lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x25b/0x340 mm/kasan/report.c:409
__asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:435
hlist_add_head include/linux/list.h:674 [inline]
xt_rateest_hash_insert net/netfilter/xt_RATEEST.c:39 [inline]
xt_rateest_tg_checkentry+0xa01/0xaa0 net/netfilter/xt_RATEEST.c:141
xt_check_target+0x22c/0x7d0 net/netfilter/x_tables.c:845
check_target net/ipv6/netfilter/ip6_tables.c:538 [inline]
find_check_entry.isra.7+0x935/0xcf0 net/ipv6/netfilter/ip6_tables.c:580
translate_table+0xf52/0x1690 net/ipv6/netfilter/ip6_tables.c:749
do_replace net/ipv6/netfilter/ip6_tables.c:1165 [inline]
do_ip6t_set_ctl+0x370/0x5f0 net/ipv6/netfilter/ip6_tables.c:1691
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
ipv6_setsockopt+0x115/0x150 net/ipv6/ipv6_sockglue.c:928
udpv6_setsockopt+0x45/0x80 net/ipv6/udp.c:1422
sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
SYSC_setsockopt net/socket.c:1849 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1828
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x446de9
RSP: 002b:00007ffc366844c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000446de9
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 00000000000000fe
RBP: 0000000000000000 R08: 00000000000003b8 R09: 00000000006d1018
R10: 0000000020019c48 R11: 0000000000000246 R12: 0000000000408310
R13: 00000000004083a0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4157:
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:551
kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610
kmalloc include/linux/slab.h:499 [inline]
kzalloc include/linux/slab.h:688 [inline]
xt_rateest_tg_checkentry+0x25a/0xaa0 net/netfilter/xt_RATEEST.c:120
xt_check_target+0x22c/0x7d0 net/netfilter/x_tables.c:845
check_target net/ipv6/netfilter/ip6_tables.c:538 [inline]
find_check_entry.isra.7+0x935/0xcf0 net/ipv6/netfilter/ip6_tables.c:580
translate_table+0xf52/0x1690 net/ipv6/netfilter/ip6_tables.c:749
do_replace net/ipv6/netfilter/ip6_tables.c:1165 [inline]
do_ip6t_set_ctl+0x370/0x5f0 net/ipv6/netfilter/ip6_tables.c:1691
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
ipv6_setsockopt+0x115/0x150 net/ipv6/ipv6_sockglue.c:928
udpv6_setsockopt+0x45/0x80 net/ipv6/udp.c:1422
sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
SYSC_setsockopt net/socket.c:1849 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1828
entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 4161:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3488 [inline]
kfree+0xd6/0x260 mm/slab.c:3803
__rcu_reclaim kernel/rcu/rcu.h:190 [inline]
rcu_do_batch kernel/rcu/tree.c:2758 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:3012 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2979 [inline]
rcu_process_callbacks+0xe94/0x17f0 kernel/rcu/tree.c:2996
__do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801afbcc200
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 88 bytes inside of
192-byte region [ffff8801afbcc200, ffff8801afbcc2c0)
The buggy address belongs to the page:
page:ffffea0006bef300 count:1 mapcount:0 mapping:ffff8801afbcc000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801afbcc000 0000000000000000 0000000100000010
raw: ffffea0006bd23a0 ffffea0006c02560 ffff8801db000040 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801afbcc100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801afbcc180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff8801afbcc200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801afbcc280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8801afbcc300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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