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authorArtem Savkov <asavkov@redhat.com>2017-09-26 18:35:45 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2017-09-29 13:36:06 +0200
commite6b72ee88a56bcfe63f72e9c30766484c45bec72 (patch)
tree6b3cafcc56342070fa0da916ddbb9672138411f1 /net/bridge
parent0d18779be13766b33c69cbc26df38383598da373 (diff)
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netfilter: ebtables: fix race condition in frame_filter_net_init()
It is possible for ebt_in_hook to be triggered before ebt_table is assigned resulting in a NULL-pointer dereference. Make sure hooks are registered as the last step. Fixes: aee12a0a3727 ("ebtables: remove nf_hook_register usage") Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/bridge')
-rw-r--r--net/bridge/netfilter/ebtable_broute.c4
-rw-r--r--net/bridge/netfilter/ebtable_filter.c4
-rw-r--r--net/bridge/netfilter/ebtable_nat.c4
-rw-r--r--net/bridge/netfilter/ebtables.c17
4 files changed, 15 insertions, 14 deletions
diff --git a/net/bridge/netfilter/ebtable_broute.c b/net/bridge/netfilter/ebtable_broute.c
index 2585b100ebbb..276b60262981 100644
--- a/net/bridge/netfilter/ebtable_broute.c
+++ b/net/bridge/netfilter/ebtable_broute.c
@@ -65,8 +65,8 @@ static int ebt_broute(struct sk_buff *skb)
static int __net_init broute_net_init(struct net *net)
{
- net->xt.broute_table = ebt_register_table(net, &broute_table, NULL);
- return PTR_ERR_OR_ZERO(net->xt.broute_table);
+ return ebt_register_table(net, &broute_table, NULL,
+ &net->xt.broute_table);
}
static void __net_exit broute_net_exit(struct net *net)
diff --git a/net/bridge/netfilter/ebtable_filter.c b/net/bridge/netfilter/ebtable_filter.c
index 45a00dbdbcad..c41da5fac84f 100644
--- a/net/bridge/netfilter/ebtable_filter.c
+++ b/net/bridge/netfilter/ebtable_filter.c
@@ -93,8 +93,8 @@ static const struct nf_hook_ops ebt_ops_filter[] = {
static int __net_init frame_filter_net_init(struct net *net)
{
- net->xt.frame_filter = ebt_register_table(net, &frame_filter, ebt_ops_filter);
- return PTR_ERR_OR_ZERO(net->xt.frame_filter);
+ return ebt_register_table(net, &frame_filter, ebt_ops_filter,
+ &net->xt.frame_filter);
}
static void __net_exit frame_filter_net_exit(struct net *net)
diff --git a/net/bridge/netfilter/ebtable_nat.c b/net/bridge/netfilter/ebtable_nat.c
index 57cd5bb154e7..08df7406ecb3 100644
--- a/net/bridge/netfilter/ebtable_nat.c
+++ b/net/bridge/netfilter/ebtable_nat.c
@@ -93,8 +93,8 @@ static const struct nf_hook_ops ebt_ops_nat[] = {
static int __net_init frame_nat_net_init(struct net *net)
{
- net->xt.frame_nat = ebt_register_table(net, &frame_nat, ebt_ops_nat);
- return PTR_ERR_OR_ZERO(net->xt.frame_nat);
+ return ebt_register_table(net, &frame_nat, ebt_ops_nat,
+ &net->xt.frame_nat);
}
static void __net_exit frame_nat_net_exit(struct net *net)
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 83951f978445..3b3dcf719e07 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1169,9 +1169,8 @@ static void __ebt_unregister_table(struct net *net, struct ebt_table *table)
kfree(table);
}
-struct ebt_table *
-ebt_register_table(struct net *net, const struct ebt_table *input_table,
- const struct nf_hook_ops *ops)
+int ebt_register_table(struct net *net, const struct ebt_table *input_table,
+ const struct nf_hook_ops *ops, struct ebt_table **res)
{
struct ebt_table_info *newinfo;
struct ebt_table *t, *table;
@@ -1183,7 +1182,7 @@ ebt_register_table(struct net *net, const struct ebt_table *input_table,
repl->entries == NULL || repl->entries_size == 0 ||
repl->counters != NULL || input_table->private != NULL) {
BUGPRINT("Bad table data for ebt_register_table!!!\n");
- return ERR_PTR(-EINVAL);
+ return -EINVAL;
}
/* Don't add one table to multiple lists. */
@@ -1252,16 +1251,18 @@ ebt_register_table(struct net *net, const struct ebt_table *input_table,
list_add(&table->list, &net->xt.tables[NFPROTO_BRIDGE]);
mutex_unlock(&ebt_mutex);
+ WRITE_ONCE(*res, table);
+
if (!ops)
- return table;
+ return 0;
ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
if (ret) {
__ebt_unregister_table(net, table);
- return ERR_PTR(ret);
+ *res = NULL;
}
- return table;
+ return ret;
free_unlock:
mutex_unlock(&ebt_mutex);
free_chainstack:
@@ -1276,7 +1277,7 @@ free_newinfo:
free_table:
kfree(table);
out:
- return ERR_PTR(ret);
+ return ret;
}
void ebt_unregister_table(struct net *net, struct ebt_table *table,