cfg80211: check regulatory request alpha2 early

Currently nl80211 allows userspace to send the kernel
a bogus regulatory domain with at most 32 rules set
and it won't reject it until after its allocated
memory. Let's be smart about it and take advantage
that the last_request is now available under RTNL
and check if the alpha2 matches an expected request
and reject any bogus userspace requests prior to
hitting the memory allocator.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 5 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 04fa8bb1b4bb..7b73132910b7 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5100,6 +5100,9 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
                         return -EINVAL;
         }
 
+        if (!reg_is_valid_request(alpha2))
+                return -EINVAL;
+
         size_of_regd = sizeof(struct ieee80211_regdomain) +
                        num_rules * sizeof(struct ieee80211_reg_rule);
 
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index b4b16871a56e..d8f047aadd49 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -450,7 +450,7 @@ static int call_crda(const char *alpha2)
         return kobject_uevent(&reg_pdev->dev.kobj, KOBJ_CHANGE);
 }
 
-static bool reg_is_valid_request(const char *alpha2)
+bool reg_is_valid_request(const char *alpha2)
 {
         struct regulatory_request *lr = get_last_request();
 
diff --git a/net/wireless/reg.h b/net/wireless/reg.h
index 9677e3c13da9..b4076babaf47 100644
--- a/net/wireless/reg.h
+++ b/net/wireless/reg.h
@@ -18,6 +18,7 @@
 
 extern const struct ieee80211_regdomain __rcu *cfg80211_regdomain;
 
+bool reg_is_valid_request(const char *alpha2);
 bool is_world_regdom(const char *alpha2);
 bool reg_supported_dfs_region(u8 dfs_region);