netfilter: x_tables: validate e->target_offset early
We should check that e->target_offset is sane before
mark_source_chains gets called since it will fetch the target entry
for loop detection.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index e53f8d6..1d72a3c 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -569,14 +569,12 @@
}
static int
-check_entry(const struct ipt_entry *e, const char *name)
+check_entry(const struct ipt_entry *e)
{
const struct xt_entry_target *t;
- if (!ip_checkentry(&e->ip)) {
- duprintf("ip check failed %p %s.\n", e, name);
+ if (!ip_checkentry(&e->ip))
return -EINVAL;
- }
if (e->target_offset + sizeof(struct xt_entry_target) >
e->next_offset)
@@ -666,10 +664,6 @@
struct xt_mtchk_param mtpar;
struct xt_entry_match *ematch;
- ret = check_entry(e, name);
- if (ret)
- return ret;
-
e->counters.pcnt = xt_percpu_counter_alloc();
if (IS_ERR_VALUE(e->counters.pcnt))
return -ENOMEM;
@@ -741,6 +735,7 @@
unsigned int valid_hooks)
{
unsigned int h;
+ int err;
if ((unsigned long)e % __alignof__(struct ipt_entry) != 0 ||
(unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
@@ -755,6 +750,10 @@
return -EINVAL;
}
+ err = check_entry(e);
+ if (err)
+ return err;
+
/* Check hooks & underflows */
for (h = 0; h < NF_INET_NUMHOOKS; h++) {
if (!(valid_hooks & (1 << h)))
@@ -1506,7 +1505,7 @@
}
/* For purposes of check_entry casting the compat entry is fine */
- ret = check_entry((struct ipt_entry *)e, name);
+ ret = check_entry((struct ipt_entry *)e);
if (ret)
return ret;