KASAN: invalid-free in kvfree

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
0f3e9c97eb5a97972b0c0076a5cc01bb142f8e70 (Tue Mar 6 05:53:44 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.
CC: [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]

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TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending
cookies. Check SNMP counters.
==================================================================
BUG: KASAN: double-free or invalid-free in kvfree+0x36/0x60 mm/util.c:438

CPU: 1 PID: 4260 Comm: syz-executor4 Not tainted 4.16.0-rc4+ #254
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_invalid_free+0x55/0x80 mm/kasan/report.c:336
__kasan_slab_free+0x145/0x170 mm/kasan/kasan.c:500
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
__cache_free mm/slab.c:3485 [inline]
kfree+0xd9/0x260 mm/slab.c:3800
kvfree+0x36/0x60 mm/util.c:438
xt_free_table_info+0xaf/0x170 net/netfilter/x_tables.c:1026
__do_replace+0x810/0xa70 net/ipv6/netfilter/ip6_tables.c:1114
do_replace net/ipv6/netfilter/ip6_tables.c:1168 [inline]
do_ip6t_set_ctl+0x40f/0x5f0 net/ipv6/netfilter/ip6_tables.c:1690
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115
ipv6_setsockopt+0x10b/0x130 net/ipv6/ipv6_sockglue.c:927
tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2878
sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2979
SYSC_setsockopt net/socket.c:1850 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1829
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45697a
RSP: 002b:0000000000a3e3b8 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000a3e3e0 RCX: 000000000045697a
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000013
RBP: 00000000006fd900 R08: 00000000000003b8 R09: 0000000000004000
R10: 00000000006fb6e0 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000013 R14: 0000000000000029 R15: 00000000006fb740

Allocated by task 7667:
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
__do_kmalloc mm/slab.c:3705 [inline]
__kmalloc_track_caller+0x15e/0x760 mm/slab.c:3720
kmemdup+0x24/0x50 mm/util.c:118
kmemdup include/linux/string.h:418 [inline]
selinux_cred_prepare+0x43/0xa0 security/selinux/hooks.c:3828
security_prepare_creds+0x7d/0xb0 security/security.c:1000
prepare_creds+0x2b1/0x360 kernel/cred.c:278
SYSC_faccessat fs/open.c:365 [inline]
SyS_faccessat fs/open.c:353 [inline]
SYSC_access fs/open.c:431 [inline]
SyS_access+0x8f/0x6a0 fs/open.c:429
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7667:
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
selinux_cred_free+0x48/0x70 security/selinux/hooks.c:3814
security_cred_free+0x48/0x80 security/security.c:995
put_cred_rcu+0x106/0x400 kernel/cred.c:117
__rcu_reclaim kernel/rcu/rcu.h:172 [inline]
rcu_do_batch kernel/rcu/tree.c:2674 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2900 [inline]
rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917
__do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801c95e2880
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
32-byte region [ffff8801c95e2880, ffff8801c95e28a0)
The buggy address belongs to the page:
page:ffffea0007257880 count:1 mapcount:0 mapping:ffff8801c95e2000
index:0xffff8801c95e2fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c95e2000 ffff8801c95e2fc1 000000010000000f
raw: ffffea0006eae820 ffffea0006bb8b20 ffff8801dac001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801c95e2780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801c95e2800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ffff8801c95e2880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
^
ffff8801c95e2900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801c95e2980: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


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[Dmitry Vyukov]

Happened once more than a month ago. There was a bunch of bugs in
netfilter fixed.

#syz invalid

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