linux-kernel - [PATCH 3.2 078/115] netfilter: x_tables: make sure e->next

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Message-ID: <lsq.1461711744.868229333@decadent.org.uk>
Date:	Wed, 27 Apr 2016 01:02:24 +0200
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Pablo Neira Ayuso" <pablo@...filter.org>,
	"Florian Westphal" <fw@...len.de>
Subject: [PATCH 3.2 078/115] netfilter: x_tables: make sure e->next_offset
 covers remaining blob size

3.2.80-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@...len.de>

commit 6e94e0cfb0887e4013b3b930fa6ab1fe6bb6ba91 upstream.

Otherwise this function may read data beyond the ruleset blob.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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(-)

--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -558,7 +558,8 @@ static inline int check_entry_size_and_h
 	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;
 	}
@@ -1218,7 +1219,8 @@ check_compat_entry_size_and_hooks(struct
 
 	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;
 	}
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -722,7 +722,8 @@ check_entry_size_and_hooks(struct ipt_en
 	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;
 	}
@@ -1485,7 +1486,8 @@ check_compat_entry_size_and_hooks(struct
 
 	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;
 	}
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -745,7 +745,8 @@ check_entry_size_and_hooks(struct ip6t_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;
 	}
@@ -1509,7 +1510,8 @@ check_compat_entry_size_and_hooks(struct
 
 	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;
 	}