wifi: nl80211: return error message for malformed chandef

Add an error message to the missing frequency case to have all
-EINVAL in nl80211_parse_chandef() return a better error.
Signed-off-by: Jaewan Kim <jaewan@google.com>
Link: https://lore.kernel.org/r/20230130074514.1560021-1-jaewan@google.com
[rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -3181,8 +3181,11 @@ int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
 	struct nlattr **attrs = info->attrs;
 	u32 control_freq;
 
-	if (!attrs[NL80211_ATTR_WIPHY_FREQ])
+	if (!attrs[NL80211_ATTR_WIPHY_FREQ]) {
+		NL_SET_ERR_MSG_ATTR(extack, attrs[NL80211_ATTR_WIPHY_FREQ],
+				    "Frequency is missing");
 		return -EINVAL;
+	}
 
 	control_freq = MHZ_TO_KHZ(
 			nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]));