cfg80211: fix in nl80211_set_reg()

There is a race on access to last_request and its alpha2
through reg_is_valid_request() and us possibly processing
first another regulatory request on another CPU. We avoid
this improbably race by locking with the cfg80211_mutex as
we should have done in the first place. While at it add
the assert on locking on reg_is_valid_request().

Cc: stable@kernel.org
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 66e0fb6a6420..632504060789 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2570,6 +2570,8 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
                         return -EINVAL;
         }
 
+        mutex_lock(&cfg80211_mutex);
+
         if (!reg_is_valid_request(alpha2)) {
                 r = -EINVAL;
                 goto bad_reg;
@@ -2607,13 +2609,14 @@ static int nl80211_set_reg(struct sk_buff *skb, struct genl_info *info)
 
         BUG_ON(rule_idx != num_rules);
 
-        mutex_lock(&cfg80211_mutex);
         r = set_regdom(rd);
+
         mutex_unlock(&cfg80211_mutex);
 
         return r;
 
  bad_reg:
+        mutex_unlock(&cfg80211_mutex);
         kfree(rd);
         return r;
 }
diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 48db569d4c6b..8d176a8010ba 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -382,6 +382,8 @@ static int call_crda(const char *alpha2)
 /* Used by nl80211 before kmalloc'ing our regulatory domain */
 bool reg_is_valid_request(const char *alpha2)
 {
+        assert_cfg80211_lock();
+
         if (!last_request)
                 return false;