mac80211: fix some snprintf misuses

In some debugfs related functions snprintf was used
while scnprintf should have been used instead.

(blindly adding the return value of snprintf and supplying
it to the next snprintf might result in buffer overflow when
the input is too big)

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/rc80211_pid_debugfs.c b/net/mac80211/rc80211_pid_debugfs.c
index c97a065..6ff1346 100644
--- a/net/mac80211/rc80211_pid_debugfs.c
+++ b/net/mac80211/rc80211_pid_debugfs.c
@@ -167,29 +167,29 @@
 	 * provide large enough buffers. */
 	length = length < RC_PID_PRINT_BUF_SIZE ?
 		 length : RC_PID_PRINT_BUF_SIZE;
-	p = snprintf(pb, length, "%u %lu ", ev->id, ev->timestamp);
+	p = scnprintf(pb, length, "%u %lu ", ev->id, ev->timestamp);
 	switch (ev->type) {
 	case RC_PID_EVENT_TYPE_TX_STATUS:
-		p += snprintf(pb + p, length - p, "tx_status %u %u",
-			      !(ev->data.flags & IEEE80211_TX_STAT_ACK),
-			      ev->data.tx_status.status.rates[0].idx);
+		p += scnprintf(pb + p, length - p, "tx_status %u %u",
+			       !(ev->data.flags & IEEE80211_TX_STAT_ACK),
+			       ev->data.tx_status.status.rates[0].idx);
 		break;
 	case RC_PID_EVENT_TYPE_RATE_CHANGE:
-		p += snprintf(pb + p, length - p, "rate_change %d %d",
-			      ev->data.index, ev->data.rate);
+		p += scnprintf(pb + p, length - p, "rate_change %d %d",
+			       ev->data.index, ev->data.rate);
 		break;
 	case RC_PID_EVENT_TYPE_TX_RATE:
-		p += snprintf(pb + p, length - p, "tx_rate %d %d",
-			      ev->data.index, ev->data.rate);
+		p += scnprintf(pb + p, length - p, "tx_rate %d %d",
+			       ev->data.index, ev->data.rate);
 		break;
 	case RC_PID_EVENT_TYPE_PF_SAMPLE:
-		p += snprintf(pb + p, length - p,
-			      "pf_sample %d %d %d %d",
-			      ev->data.pf_sample, ev->data.prop_err,
-			      ev->data.int_err, ev->data.der_err);
+		p += scnprintf(pb + p, length - p,
+			       "pf_sample %d %d %d %d",
+			       ev->data.pf_sample, ev->data.prop_err,
+			       ev->data.int_err, ev->data.der_err);
 		break;
 	}
-	p += snprintf(pb + p, length - p, "\n");
+	p += scnprintf(pb + p, length - p, "\n");
 
 	spin_unlock_irqrestore(&events->lock, status);