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>

net/mac80211/debugfs.c

@@ -103,54 +103,57 @@ static ssize_t hwflags_read(struct file *file, char __user *user_buf,
 	if (!buf)
 		return 0;
 
-	sf += snprintf(buf, mxln - sf, "0x%x\n", local->hw.flags);
+	sf += scnprintf(buf, mxln - sf, "0x%x\n", local->hw.flags);
 	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
-		sf += snprintf(buf + sf, mxln - sf, "HAS_RATE_CONTROL\n");
+		sf += scnprintf(buf + sf, mxln - sf, "HAS_RATE_CONTROL\n");
 	if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
-		sf += snprintf(buf + sf, mxln - sf, "RX_INCLUDES_FCS\n");
+		sf += scnprintf(buf + sf, mxln - sf, "RX_INCLUDES_FCS\n");
 	if (local->hw.flags & IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING)
-		sf += snprintf(buf + sf, mxln - sf,
+		sf += scnprintf(buf + sf, mxln - sf,
 				"HOST_BCAST_PS_BUFFERING\n");
 	if (local->hw.flags & IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE)
-		sf += snprintf(buf + sf, mxln - sf,
+		sf += scnprintf(buf + sf, mxln - sf,
 				"2GHZ_SHORT_SLOT_INCAPABLE\n");
 	if (local->hw.flags & IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE)
-		sf += snprintf(buf + sf, mxln - sf,
+		sf += scnprintf(buf + sf, mxln - sf,
 				"2GHZ_SHORT_PREAMBLE_INCAPABLE\n");
 	if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
-		sf += snprintf(buf + sf, mxln - sf, "SIGNAL_UNSPEC\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SIGNAL_UNSPEC\n");
 	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
-		sf += snprintf(buf + sf, mxln - sf, "SIGNAL_DBM\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SIGNAL_DBM\n");
 	if (local->hw.flags & IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC)
-		sf += snprintf(buf + sf, mxln - sf, "NEED_DTIM_BEFORE_ASSOC\n");
+		sf += scnprintf(buf + sf, mxln - sf,
+				"NEED_DTIM_BEFORE_ASSOC\n");
 	if (local->hw.flags & IEEE80211_HW_SPECTRUM_MGMT)
-		sf += snprintf(buf + sf, mxln - sf, "SPECTRUM_MGMT\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SPECTRUM_MGMT\n");
 	if (local->hw.flags & IEEE80211_HW_AMPDU_AGGREGATION)
-		sf += snprintf(buf + sf, mxln - sf, "AMPDU_AGGREGATION\n");
+		sf += scnprintf(buf + sf, mxln - sf, "AMPDU_AGGREGATION\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_PS)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_PS\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SUPPORTS_PS\n");
 	if (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK)
-		sf += snprintf(buf + sf, mxln - sf, "PS_NULLFUNC_STACK\n");
+		sf += scnprintf(buf + sf, mxln - sf, "PS_NULLFUNC_STACK\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_PS)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_DYNAMIC_PS\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SUPPORTS_DYNAMIC_PS\n");
 	if (local->hw.flags & IEEE80211_HW_MFP_CAPABLE)
-		sf += snprintf(buf + sf, mxln - sf, "MFP_CAPABLE\n");
+		sf += scnprintf(buf + sf, mxln - sf, "MFP_CAPABLE\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_STATIC_SMPS)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_STATIC_SMPS\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SUPPORTS_STATIC_SMPS\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_DYNAMIC_SMPS\n");
+		sf += scnprintf(buf + sf, mxln - sf,
+				"SUPPORTS_DYNAMIC_SMPS\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_UAPSD)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_UAPSD\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SUPPORTS_UAPSD\n");
 	if (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS)
-		sf += snprintf(buf + sf, mxln - sf, "REPORTS_TX_ACK_STATUS\n");
+		sf += scnprintf(buf + sf, mxln - sf,
+				"REPORTS_TX_ACK_STATUS\n");
 	if (local->hw.flags & IEEE80211_HW_CONNECTION_MONITOR)
-		sf += snprintf(buf + sf, mxln - sf, "CONNECTION_MONITOR\n");
+		sf += scnprintf(buf + sf, mxln - sf, "CONNECTION_MONITOR\n");
 	if (local->hw.flags & IEEE80211_HW_SUPPORTS_PER_STA_GTK)
-		sf += snprintf(buf + sf, mxln - sf, "SUPPORTS_PER_STA_GTK\n");
+		sf += scnprintf(buf + sf, mxln - sf, "SUPPORTS_PER_STA_GTK\n");
 	if (local->hw.flags & IEEE80211_HW_AP_LINK_PS)
-		sf += snprintf(buf + sf, mxln - sf, "AP_LINK_PS\n");
+		sf += scnprintf(buf + sf, mxln - sf, "AP_LINK_PS\n");
 	if (local->hw.flags & IEEE80211_HW_TX_AMPDU_SETUP_IN_HW)
-		sf += snprintf(buf + sf, mxln - sf, "TX_AMPDU_SETUP_IN_HW\n");
+		sf += scnprintf(buf + sf, mxln - sf, "TX_AMPDU_SETUP_IN_HW\n");
 
 	rv = simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
 	kfree(buf);

net/mac80211/rc80211_pid_debugfs.c

@@ -167,29 +167,29 @@ static ssize_t rate_control_pid_events_read(struct file *file, char __user *buf,
 	 * 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",
+		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",
+		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",
+		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,
+		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);
 

net/wireless/debugfs.c

@@ -47,17 +47,19 @@ static int ht_print_chan(struct ieee80211_channel *chan,
 		return 0;
 
 	if (chan->flags & IEEE80211_CHAN_DISABLED)
-		return snprintf(buf + offset,
+		return scnprintf(buf + offset,
 				 buf_size - offset,
 				 "%d Disabled\n",
 				 chan->center_freq);
 
-	return snprintf(buf + offset,
+	return scnprintf(buf + offset,
 			 buf_size - offset,
 			 "%d HT40 %c%c\n",
 			 chan->center_freq,
-			(chan->flags & IEEE80211_CHAN_NO_HT40MINUS) ? ' ' : '-',
-			(chan->flags & IEEE80211_CHAN_NO_HT40PLUS)  ? ' ' : '+');
+			 (chan->flags & IEEE80211_CHAN_NO_HT40MINUS) ?
+				' ' : '-',
+			 (chan->flags & IEEE80211_CHAN_NO_HT40PLUS) ?
+				' ' : '+');
 }
 
 static ssize_t ht40allow_map_read(struct file *file,