[added to the 4.1 stable tree] netfilter: x_tables: make sure e->next_offset covers remaining blob size

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From: Florian Westphal <fw@xxxxxxxxx>

This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 6e94e0cfb0887e4013b3b930fa6ab1fe6bb6ba91 ]

Otherwise this function may read data beyond the ruleset blob.

Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
 net/ipv4/netfilter/arp_tables.c | 6 ++++--
 net/ipv4/netfilter/ip_tables.c  | 6 ++++--
 net/ipv6/netfilter/ip6_tables.c | 6 ++++--
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index e500f4f..835b768 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -562,7 +562,8 @@ 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;
 	}
@@ -1225,7 +1226,8 @@ 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 a75ff8a84..4ad5576 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -725,7 +725,8 @@ 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;
 	}
@@ -1491,7 +1492,8 @@ 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 ef764a6..9a4666b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -739,7 +739,8 @@ 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;
 	}
@@ -1506,7 +1507,8 @@ 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;
 	}
-- 
2.5.0

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