KASAN: slab-out-of-bounds Write in tcp_v6_syn_recv_sock

[syzbot]

Hello,

syzkaller hit the following crash on
61233580f1f33c50e159c50e24d80ffd2ba2e06b
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6dc95b...@syzkaller.appspotmail.com
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TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending
cookies. Check SNMP counters.
==================================================================
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:344 [inline]
BUG: KASAN: slab-out-of-bounds in tcp_v6_syn_recv_sock+0x628/0x23a0
net/ipv6/tcp_ipv6.c:1144
Write of size 160 at addr ffff8801cbdd7460 by task syzkaller545407/3196

CPU: 1 PID: 3196 Comm: syzkaller545407 Not tainted 4.15.0-rc5+ #241
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__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
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
memcpy+0x37/0x50 mm/kasan/kasan.c:303
memcpy include/linux/string.h:344 [inline]
tcp_v6_syn_recv_sock+0x628/0x23a0 net/ipv6/tcp_ipv6.c:1144
tcp_get_cookie_sock+0x102/0x540 net/ipv4/syncookies.c:213
cookie_v6_check+0x177d/0x2160 net/ipv6/syncookies.c:255
tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1008 [inline]
tcp_v6_do_rcv+0xe4d/0x11c0 net/ipv6/tcp_ipv6.c:1316
tcp_v6_rcv+0x22ee/0x2b40 net/ipv6/tcp_ipv6.c:1510
ip6_input_finish+0x36f/0x1700 net/ipv6/ip6_input.c:284
NF_HOOK include/linux/netfilter.h:250 [inline]
ip6_input+0xe9/0x560 net/ipv6/ip6_input.c:327
dst_input include/net/dst.h:466 [inline]
ip6_rcv_finish+0x1a9/0x7a0 net/ipv6/ip6_input.c:71
NF_HOOK include/linux/netfilter.h:250 [inline]
ipv6_rcv+0xf1f/0x1f80 net/ipv6/ip6_input.c:208
__netif_receive_skb_core+0x1a3e/0x3450 net/core/dev.c:4461
__netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4526
process_backlog+0x203/0x740 net/core/dev.c:5205
napi_poll net/core/dev.c:5603 [inline]
net_rx_action+0x792/0x1910 net/core/dev.c:5669
__do_softirq+0x2d7/0xb85 kernel/softirq.c:285
do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1115
</IRQ>
do_softirq.part.21+0x14d/0x190 kernel/softirq.c:329
do_softirq kernel/softirq.c:177 [inline]
__local_bh_enable_ip+0x1ee/0x230 kernel/softirq.c:182
local_bh_enable include/linux/bottom_half.h:32 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:727 [inline]
ip6_finish_output2+0xba6/0x2390 net/ipv6/ip6_output.c:121
ip6_finish_output+0x2f9/0x920 net/ipv6/ip6_output.c:146
NF_HOOK_COND include/linux/netfilter.h:239 [inline]
ip6_output+0x1eb/0x840 net/ipv6/ip6_output.c:163
dst_output include/net/dst.h:460 [inline]
NF_HOOK include/linux/netfilter.h:250 [inline]
ip6_xmit+0xd75/0x2080 net/ipv6/ip6_output.c:269
inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
tcp_transmit_skb+0x1b12/0x38b0 net/ipv4/tcp_output.c:1176
tcp_write_xmit+0x680/0x5190 net/ipv4/tcp_output.c:2367
__tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2543
tcp_send_fin+0x1b0/0xd20 net/ipv4/tcp_output.c:3087
tcp_close+0xbe0/0xfc0 net/ipv4/tcp.c:2234
inet_release+0xed/0x1c0 net/ipv4/af_inet.c:426
inet6_release+0x50/0x70 net/ipv6/af_inet6.c:432
sock_release+0x8d/0x1e0 net/socket.c:600
sock_close+0x16/0x20 net/socket.c:1129
__fput+0x327/0x7e0 fs/file_table.c:210
____fput+0x15/0x20 fs/file_table.c:244
task_work_run+0x199/0x270 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x9bb/0x1ad0 kernel/exit.c:865
do_group_exit+0x149/0x400 kernel/exit.c:968
get_signal+0x73f/0x16c0 kernel/signal.c:2335
do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:809
exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
entry_SYSCALL_64_fastpath+0x94/0x96
RIP: 0033:0x4456e9
RSP: 002b:00007fb4de631da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dac3c RCX: 00000000004456e9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dac3c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac38
R13: 0100000000000000 R14: 00007fb4de6329c0 R15: 0000000000000009

Allocated by task 3196:
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
kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
sk_prot_alloc+0x65/0x2a0 net/core/sock.c:1463
sk_clone_lock+0x152/0x1570 net/core/sock.c:1649
inet_csk_clone_lock+0x92/0x4f0 net/ipv4/inet_connection_sock.c:781
tcp_create_openreq_child+0x9b/0x1b70 net/ipv4/tcp_minisocks.c:449
tcp_v6_syn_recv_sock+0x22d/0x23a0 net/ipv6/tcp_ipv6.c:1123
tcp_get_cookie_sock+0x102/0x540 net/ipv4/syncookies.c:213
cookie_v6_check+0x177d/0x2160 net/ipv6/syncookies.c:255
tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1008 [inline]
tcp_v6_do_rcv+0xe4d/0x11c0 net/ipv6/tcp_ipv6.c:1316
tcp_v6_rcv+0x22ee/0x2b40 net/ipv6/tcp_ipv6.c:1510
ip6_input_finish+0x36f/0x1700 net/ipv6/ip6_input.c:284
NF_HOOK include/linux/netfilter.h:250 [inline]
ip6_input+0xe9/0x560 net/ipv6/ip6_input.c:327
dst_input include/net/dst.h:466 [inline]
ip6_rcv_finish+0x1a9/0x7a0 net/ipv6/ip6_input.c:71
NF_HOOK include/linux/netfilter.h:250 [inline]
ipv6_rcv+0xf1f/0x1f80 net/ipv6/ip6_input.c:208
__netif_receive_skb_core+0x1a3e/0x3450 net/core/dev.c:4461
__netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4526
process_backlog+0x203/0x740 net/core/dev.c:5205
napi_poll net/core/dev.c:5603 [inline]
net_rx_action+0x792/0x1910 net/core/dev.c:5669
__do_softirq+0x2d7/0xb85 kernel/softirq.c:285

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801cbdd6a80
which belongs to the cache TCP of size 2528
The buggy address is located 0 bytes to the right of
2528-byte region [ffff8801cbdd6a80, ffff8801cbdd7460)
The buggy address belongs to the page:
page:000000006145927c count:1 mapcount:0 mapping:00000000d41dd7c1
index:0xffff8801cbdd7ffd compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801cbdd6000 ffff8801cbdd7ffd 0000000100000003
raw: ffffea00074ef120 ffff8801d82b7248 ffff8801d798b640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801cbdd7300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801cbdd7380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff8801cbdd7400: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
^
ffff8801cbdd7480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801cbdd7500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[Cong Wang]

tls_init() changes sk->sk_prot from IPv6 to IPv4, which leads
to this bug. I guess IPv6 is not supported for TLS? If so, need
a check on proto in tls_init()...

[Ozgur]

03.01.2018, 21:57, "Cong Wang" <xiyou.w...@gmail.com>:

Hello,

I think IPv6 supports with TLS.
There was a previously posted commit by Mellanox:

https://patchwork.ozlabs.org/patch/801530/

Ozgur

[Cong Wang]

Good to know.

Can you resend the fix? It could probably fix another warning
reported by syzbot too.

[Dmitry Vyukov]

FTR this has been assigned CVE-2018-5703

[Wei Wang]

What is the status on resending the patch?
(https://patchwork.ozlabs.org/patch/801530/)
Another slab-out-of-bound report that could be fixed by it:

syzbot has found reproducer for the following crash on
6bd39bc3da0f4a301fae69c4a32db2768f5118be
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master

compiler: gcc (GCC) 7.1.1 20170620

==================================================================
BUG: KASAN: slab-out-of-bounds in ip6_dst_idev
include/net/ip6_fib.h:192 [inline]
BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x1ce9/0x2090
net/ipv6/ip6_output.c:264
Read of size 8 at addr ffff8801d99a1018 by task syzkaller716686/3664

CPU: 0 PID: 3664 Comm: syzkaller716686 Not tainted 4.15.0-rc7+ #187

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_load8_noabort+0x14/0x20 mm/kasan/report.c:430
ip6_dst_idev include/net/ip6_fib.h:192 [inline]
ip6_xmit+0x1ce9/0x2090 net/ipv6/ip6_output.c:264
inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
tcp_transmit_skb+0x1b1b/0x38c0 net/ipv4/tcp_output.c:1176
tcp_send_syn_data net/ipv4/tcp_output.c:3457 [inline]
tcp_connect+0x1edb/0x4090 net/ipv4/tcp_output.c:3496
tcp_v4_connect+0x15ef/0x1e70 net/ipv4/tcp_ipv4.c:257
__inet_stream_connect+0x2d4/0xf00 net/ipv4/af_inet.c:620
tcp_sendmsg_fastopen net/ipv4/tcp.c:1168 [inline]
tcp_sendmsg_locked+0x264e/0x3c70 net/ipv4/tcp.c:1214
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1463
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:640
___sys_sendmsg+0x320/0x8b0 net/socket.c:2020
__sys_sendmmsg+0x1ee/0x620 net/socket.c:2110
SYSC_sendmmsg net/socket.c:2141 [inline]
SyS_sendmmsg+0x35/0x60 net/socket.c:2136
entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x43fdd9
RSP: 002b:00007ffcaf235288 EFLAGS: 00000217 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fdd9
RDX: 0000000000000001 RSI: 00000000205f8fc8 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000217 R12: 0000000000401740
R13: 00000000004017d0 R14: 0000000000000000 R15: 0000000000000000

[Eric Biggers]

No longer occurring; last occurrence was on Jan 19 (commit dda3e15231b35).
The fix was commit d91c3e17f75f2:

#syz fix: net/tls: Only attach to sockets in ESTABLISHED state

- Eric