netfilter: ip_tables: fix infoleak to userspace
commit 78b79876761b86653df89c48a7010b5cbd41a84a 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 and the third bugs were introduced before the git epoch; the
second was introduced in 2722971c (v2.6.17-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/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index b29c66d..c89ac49 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1294,6 +1294,7 @@
/* 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)
@@ -1838,6 +1839,7 @@
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)
@@ -2067,6 +2069,7 @@
ret = -EFAULT;
break;
}
+ rev.name[sizeof(rev.name)-1] = 0;
if (cmd == IPT_SO_GET_REVISION_TARGET)
target = 1;
