[PATCH 1/5] net/usb/r8152: fix tx/rx memory overflow

[Hayes Wang <hayeswang@realtek.com>]

The tx/rx would access the memory which is out of the desired range.
Modify the method of checking the end of the memory to avoid it.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
---
 drivers/net/usb/r8152.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index f3fce41..5dbfe50 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -24,7 +24,7 @@
 #include <linux/ipv6.h>
 
 /* Version Information */
-#define DRIVER_VERSION "v1.01.0 (2013/08/12)"
+#define DRIVER_VERSION "v1.02.0 (2013/10/28)"
 #define DRIVER_AUTHOR "Realtek linux nic maintainers <nic_swsd@realtek.com>"
 #define DRIVER_DESC "Realtek RTL8152 Based USB 2.0 Ethernet Adapters"
 #define MODULENAME "r8152"
@@ -1136,14 +1136,14 @@ r8152_tx_csum(struct r8152 *tp, struct tx_desc *desc, struct sk_buff *skb)
 
 static int r8152_tx_agg_fill(struct r8152 *tp, struct tx_agg *agg)
 {
-	u32 remain;
+	int remain;
 	u8 *tx_data;
 
 	tx_data = agg->head;
 	agg->skb_num = agg->skb_len = 0;
-	remain = rx_buf_sz - sizeof(struct tx_desc);
+	remain = rx_buf_sz;
 
-	while (remain >= ETH_ZLEN) {
+	while (remain >= ETH_ZLEN + sizeof(struct tx_desc)) {
 		struct tx_desc *tx_desc;
 		struct sk_buff *skb;
 		unsigned int len;
@@ -1152,12 +1152,14 @@ static int r8152_tx_agg_fill(struct r8152 *tp, struct tx_agg *agg)
 		if (!skb)
 			break;
 
+		remain -= sizeof(*tx_desc);
 		len = skb->len;
 		if (remain < len) {
 			skb_queue_head(&tp->tx_queue, skb);
 			break;
 		}
 
+		tx_data = tx_agg_align(tx_data);
 		tx_desc = (struct tx_desc *)tx_data;
 		tx_data += sizeof(*tx_desc);
 
@@ -1167,9 +1169,8 @@ static int r8152_tx_agg_fill(struct r8152 *tp, struct tx_agg *agg)
 		agg->skb_len += len;
 		dev_kfree_skb_any(skb);
 
-		tx_data = tx_agg_align(tx_data + len);
-		remain = rx_buf_sz - sizeof(*tx_desc) -
-			 (u32)((void *)tx_data - agg->head);
+		tx_data += len;
+		remain = rx_buf_sz - (int)(tx_agg_align(tx_data) - agg->head);
 	}
 
 	usb_fill_bulk_urb(agg->urb, tp->udev, usb_sndbulkpipe(tp->udev, 2),
@@ -1188,7 +1189,6 @@ static void rx_bottom(struct r8152 *tp)
 	list_for_each_safe(cursor, next, &tp->rx_done) {
 		struct rx_desc *rx_desc;
 		struct rx_agg *agg;
-		unsigned pkt_len;
 		int len_used = 0;
 		struct urb *urb;
 		u8 *rx_data;
@@ -1204,17 +1204,22 @@ static void rx_bottom(struct r8152 *tp)
 
 		rx_desc = agg->head;
 		rx_data = agg->head;
-		pkt_len = le32_to_cpu(rx_desc->opts1) & RX_LEN_MASK;
-		len_used += sizeof(struct rx_desc) + pkt_len;
+		len_used += sizeof(struct rx_desc);
 
-		while (urb->actual_length >= len_used) {
+		while (urb->actual_length > len_used) {
 			struct net_device *netdev = tp->netdev;
 			struct net_device_stats *stats;
+			unsigned pkt_len;
 			struct sk_buff *skb;
 
+			pkt_len = le32_to_cpu(rx_desc->opts1) & RX_LEN_MASK;
 			if (pkt_len < ETH_ZLEN)
 				break;
 
+			len_used += pkt_len;
+			if (urb->actual_length < len_used)
+				break;
+
 			stats = rtl8152_get_stats(netdev);
 
 			pkt_len -= 4; /* CRC */
@@ -1234,9 +1239,8 @@ static void rx_bottom(struct r8152 *tp)
 
 			rx_data = rx_agg_align(rx_data + pkt_len + 4);
 			rx_desc = (struct rx_desc *)rx_data;
-			pkt_len = le32_to_cpu(rx_desc->opts1) & RX_LEN_MASK;
 			len_used = (int)(rx_data - (u8 *)agg->head);
-			len_used += sizeof(struct rx_desc) + pkt_len;
+			len_used += sizeof(struct rx_desc);
 		}
 
 submit:
-- 
1.8.3.1