[PATCH 6/6] ipv6: netfilter: ip6_tables: fix infoleak to userspace CVE-2011-1172

[Stefan Bader]

On 04.07.2011 16:08, paolo.pisati at canonical.com wrote:
> From: Vasiliy Kulikov <segoon at openwall.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/801483
> 
> commit upstream 6a8ab060779779de8aea92ce3337ca348f973f54
> 
> Structures ip6t_replace, compat_ip6t_replace, and xt_get_revision are
> copied from userspace.  Fields of these structs that are
> zero-terminated strings are not checked.  When they are used as argument
> to a format string containing "%s" in request_module(), some sensitive
> information is leaked to userspace via argument of spawned modprobe
> process.
> 
> The first bug was introduced before the git epoch;  the second was
> introduced in 3bc3fe5e (v2.6.25-rc1);  the third is introduced by
> 6b7d31fc (v2.6.15-rc1).  To trigger the bug one should have
> CAP_NET_ADMIN.
> 
> CVE-2011-1172
> 
> Signed-off-by: Vasiliy Kulikov <segoon at openwall.com>
> Signed-off-by: Patrick McHardy <kaber at trash.net>
> Signed-off-by: Paolo Pisati <paolo.pisati at canonical.com>
> ---
>  net/ipv6/netfilter/ip6_tables.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
> index acaba15..68fb45e 100644
> --- a/net/ipv6/netfilter/ip6_tables.c
> +++ b/net/ipv6/netfilter/ip6_tables.c
> @@ -1047,6 +1047,7 @@ do_replace(void __user *user, unsigned int len)
>  		return -ENOMEM;
>  	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
>  		return -ENOMEM;
> +	tmp.name[sizeof(tmp.name)-1] = 0;
>  
>  	newinfo = xt_alloc_table_info(tmp.size);
>  	if (!newinfo)

Same as for previous patch. Just to be sure below hunk is right.

> @@ -1162,6 +1163,7 @@ do_add_counters(void __user *user, unsigned int len)
>  
>  	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
>  		return -EFAULT;
> +	tmp.name[sizeof(tmp.name)-1] = 0;
>  
>  	if (len != sizeof(tmp) + tmp.num_counters*sizeof(struct xt_counters))
>  		return -EINVAL;

> @@ -1313,6 +1315,7 @@ do_ip6t_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>  			ret = -EFAULT;
>  			break;
>  		}
> +		rev.name[sizeof(rev.name)-1] = 0;
>  
>  		if (cmd == IP6T_SO_GET_REVISION_TARGET)
>  			target = 1;