netfilter: xt_socket: Restore mark from full sockets only

An out of bounds error was detected on an ARM64 target with
Android based kernel 4.9. This occurs while trying to
restore mark on a skb from an inet request socket.

BUG: KASAN: slab-out-of-bounds in socket_match.isra.2+0xc8/0x1f0 net/netfilter/xt_socket.c:248
Read of size 4 at addr ffffffc06a8d824c by task syz-fuzzer/1532
CPU: 7 PID: 1532 Comm: syz-fuzzer Tainted: G        W  O    4.9.41+ #1
Call trace:
[<ffffff900808d2f8>] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:76
[<ffffff900808d760>] show_stack+0x28/0x38 arch/arm64/kernel/traps.c:226
[<ffffff90085f7dc8>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffff90085f7dc8>] dump_stack+0xe4/0x134 lib/dump_stack.c:51
[<ffffff900830f358>] print_address_description+0x68/0x258 mm/kasan/report.c:248
[<ffffff900830f770>] kasan_report_error mm/kasan/report.c:347 [inline]
[<ffffff900830f770>] kasan_report.part.2+0x228/0x2f0 mm/kasan/report.c:371
[<ffffff900830fdec>] kasan_report+0x5c/0x70 mm/kasan/report.c:372
[<ffffff900830de98>] check_memory_region_inline mm/kasan/kasan.c:308 [inline]
[<ffffff900830de98>] __asan_load4+0x88/0xa0 mm/kasan/kasan.c:740
[<ffffff90097498f8>] socket_match.isra.2+0xc8/0x1f0 net/netfilter/xt_socket.c:248
[<ffffff9009749a5c>] socket_mt4_v1_v2_v3+0x3c/0x48 net/netfilter/xt_socket.c:272
[<ffffff90097f7e4c>] ipt_do_table+0x54c/0xad8 net/ipv4/netfilter/ip_tables.c:311
[<ffffff90097fcf14>] iptable_mangle_hook+0x6c/0x220 net/ipv4/netfilter/iptable_mangle.c:90
...
Allocated by task 1532:
 save_stack_trace_tsk+0x0/0x2a0 arch/arm64/kernel/stacktrace.c:131
 save_stack_trace+0x28/0x38 arch/arm64/kernel/stacktrace.c:215
 save_stack mm/kasan/kasan.c:495 [inline]
 set_track mm/kasan/kasan.c:507 [inline]
 kasan_kmalloc+0xd8/0x188 mm/kasan/kasan.c:599
 kasan_slab_alloc+0x14/0x20 mm/kasan/kasan.c:537
 slab_post_alloc_hook mm/slab.h:417 [inline]
 slab_alloc_node mm/slub.c:2728 [inline]
 slab_alloc mm/slub.c:2736 [inline]
 kmem_cache_alloc+0x14c/0x2e8 mm/slub.c:2741
 reqsk_alloc include/net/request_sock.h:87 [inline]
 inet_reqsk_alloc+0x4c/0x238 net/ipv4/tcp_input.c:6236
 tcp_conn_request+0x2b0/0xea8 net/ipv4/tcp_input.c:6341
 tcp_v4_conn_request+0xe0/0x100 net/ipv4/tcp_ipv4.c:1256
 tcp_rcv_state_process+0x384/0x18a8 net/ipv4/tcp_input.c:5926
 tcp_v4_do_rcv+0x2f0/0x3e0 net/ipv4/tcp_ipv4.c:1430
 tcp_v4_rcv+0x1278/0x1350 net/ipv4/tcp_ipv4.c:1709
 ip_local_deliver_finish+0x174/0x3e0 net/ipv4/ip_input.c:216

Fixes: a94070000388 ("netfilter: xt_socket: prepare for TCP_NEW_SYN_RECV support")
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
---
 net/netfilter/xt_socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

On Thu, 2017-09-21 at 15:20 -0600, Subash Abhinov Kasiviswanathan wrote:
> An out of bounds error was detected on an ARM64 target with
> Android based kernel 4.9. This occurs while trying to
> restore mark on a skb from an inet request socket.
> 
> BUG: KASAN: slab-out-of-bounds in socket_match.isra.2+0xc8/0x1f0 net/netfilter/xt_socket.c:248

...

> 
> Fixes: a94070000388 ("netfilter: xt_socket: prepare for TCP_NEW_SYN_RECV support")
> Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
> ---
>  net/netfilter/xt_socket.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
> index e75ef39..3301091 100644
> --- a/net/netfilter/xt_socket.c
> +++ b/net/netfilter/xt_socket.c
> @@ -76,7 +76,7 @@
>  			transparent = nf_sk_is_transparent(sk);
>  
>  		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
> -		    transparent)
> +		    transparent && sk_fullsock(sk))
>  			pskb->mark = sk->sk_mark;
>  
>  		if (sk != skb->sk)

What about socket_mt6_v1_v2_v3() ?

Thanks.


--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

>> 
>>  		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
>> -		    transparent)
>> +		    transparent && sk_fullsock(sk))
>>  			pskb->mark = sk->sk_mark;
>> 
>>  		if (sk != skb->sk)
> 
> What about socket_mt6_v1_v2_v3() ?
> 
> Thanks.

Hi Eric

I missed that instance. I'll update it in v2.