netfilter: x_tables: make sure e->next_offset covers remaining blob size

commit 6e94e0cfb0887e4013b3b930fa6ab1fe6bb6ba91 upstream.

Otherwise this function may read data beyond the ruleset blob.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 3d45ce5cb6d8ab76732c37907daeac8da0bd387b..91af0ee6680afe8365f85dcee8af6d61daff1ebc 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -563,7 +563,8 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
        int err;
 
        if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p\n", e);
                return -EINVAL;
        }
@@ -1223,7 +1224,8 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
 
        duprintf("check_compat_entry_size_and_hooks %p\n", e);
        if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p, limit = %p\n", e, limit);
                return -EINVAL;
        }

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index ae55a383eb9687dc835e0215ea386f7f797334b0..ec32ca649c58819d9e845fe279ccc7329195a76e 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -726,7 +726,8 @@ check_entry_size_and_hooks(struct ipt_entry *e,
        int err;
 
        if ((unsigned long)e % __alignof__(struct ipt_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct ipt_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p\n", e);
                return -EINVAL;
        }
@@ -1489,7 +1490,8 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
 
        duprintf("check_compat_entry_size_and_hooks %p\n", e);
        if ((unsigned long)e % __alignof__(struct compat_ipt_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct compat_ipt_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct compat_ipt_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p, limit = %p\n", e, limit);
                return -EINVAL;
        }

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 16241623f138ecc82a21350fe8beb6f0e0646805..e8713a3fd7ab791601bda31c11fa2e4fd6238f93 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -737,7 +737,8 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
        int err;
 
        if ((unsigned long)e % __alignof__(struct ip6t_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct ip6t_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct ip6t_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p\n", e);
                return -EINVAL;
        }
@@ -1501,7 +1502,8 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
 
        duprintf("check_compat_entry_size_and_hooks %p\n", e);
        if ((unsigned long)e % __alignof__(struct compat_ip6t_entry) != 0 ||
-           (unsigned char *)e + sizeof(struct compat_ip6t_entry) >= limit) {
+           (unsigned char *)e + sizeof(struct compat_ip6t_entry) >= limit ||
+           (unsigned char *)e + e->next_offset > limit) {
                duprintf("Bad offset %p, limit = %p\n", e, limit);
                return -EINVAL;
        }