[081/105] netfilter: arp_tables: fix infoleak to userspace

Greg KH
2011-04-12T14:38:48Z

From: Vasiliy Kulikov <segoon@openwall.com>

commit 42eab94fff18cb1091d3501cd284d6bd6cc9c143 upstream.

Structures ipt_replace, compat_ipt_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 is
introduced by 6b7d31fc (v2.6.15-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: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/netfilter/arp_tables.c | 3 +++
1 file changed, 3 insertions(+)

--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1065,6 +1065,7 @@ static int do_replace(struct net *net, c
/* 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)
@@ -1486,6 +1487,7 @@ static int compat_do_replace(struct net
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)
@@ -1738,6 +1740,7 @@ static int do_arpt_get_ctl(struct sock *
ret = -EFAULT;
break;
}
+ rev.name[sizeof(rev.name)-1] = 0;

try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
rev.revision, 1, &ret),