cfg80211: protect first access of last_request on 11d hint under mutex

We were not protecting last_request there is a small possible race
between an 11d hint and another routine which calls reset_regdomains()
which can prevent a valid country IE from being processed. This is
not critical as it will still be procesed soon after but locking prior
to it is correct.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index d44f3b5481ad..b47445219a48 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -1261,11 +1261,13 @@ void regulatory_hint_11d(struct wiphy *wiphy,
         u32 checksum = 0;
         enum environment_cap env = ENVIRON_ANY;
 
-        if (!last_request)
-                return;
-
         mutex_lock(&cfg80211_mutex);
 
+        if (unlikely(!last_request)) {
+                mutex_unlock(&cfg80211_mutex);
+                return;
+        }
+
         /* IE len must be evenly divisible by 2 */
         if (country_ie_len & 0x01)
                 goto out;