ipv6: netfilter: ip6_tables: fix infoleak to userspace

commit 6a8ab060779779de8aea92ce3337ca348f973f54 upstream.

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.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 9210e312edf1d41a62cf336ec3287329060f3fa9..542edbfa752f2b05423bf151545eed371cab9de5 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1325,6 +1325,7 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
        /* overflow check */
        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)
@@ -1871,6 +1872,7 @@ compat_do_replace(struct net *net, 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)
@@ -2100,6 +2102,7 @@ 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;