asix: Ensure asix_rx_fixup_info members are all reset

There is a risk that the members of the structure asix_rx_fixup_info
become unsynchronised leading to the possibility of a malfunction.

For example, rx->split_head was not being set to false after an
error was detected so potentially could cause a malformed 32-bit
Data header word to be formed.

Therefore add function reset_asix_rx_fixup_info() to reset all the
members of asix_rx_fixup_info so that future processing will start
with known initial conditions.

Also, if (skb->len != offset) becomes true then call
reset_asix_rx_fixup_info() so that the processing of the next URB
starts with known initial conditions. Without the call, the check
does nothing which potentially could lead to a malfunction
when the next URB is processed.

In addition, for robustness, call reset_asix_rx_fixup_info() before
every error path's "return 0". This ensures that the next URB is
processed from known initial conditions.

Signed-off-by: Dean Jenkins <Dean_Jenkins@mentor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index 6983b6bd8cf9499666c3d7ea6bab2c93fc6c6b4b..fda74f33e3ece1d5ec2928b0e2ee0473f832e057 100644 (file)
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -75,6 +75,27 @@ void asix_write_cmd_async(struct usbnet *dev, u8 cmd, u16 value, u16 index,
                               value, index, data, size);
 }
 
+static void reset_asix_rx_fixup_info(struct asix_rx_fixup_info *rx)
+{
+       /* Reset the variables that have a lifetime outside of
+        * asix_rx_fixup_internal() so that future processing starts from a
+        * known set of initial conditions.
+        */
+
+       if (rx->ax_skb) {
+               /* Discard any incomplete Ethernet frame in the netdev buffer */
+               kfree_skb(rx->ax_skb);
+               rx->ax_skb = NULL;
+       }
+
+       /* Assume the Data header 32-bit word is at the start of the current
+        * or next URB socket buffer so reset all the state variables.
+        */
+       rx->remaining = 0;
+       rx->split_head = false;
+       rx->header = 0;
+}
+
 int asix_rx_fixup_internal(struct usbnet *dev, struct sk_buff *skb,
                           struct asix_rx_fixup_info *rx)
 {
@@ -99,15 +120,7 @@ int asix_rx_fixup_internal(struct usbnet *dev, struct sk_buff *skb,
                if (size != ((~rx->header >> 16) & 0x7ff)) {
                        netdev_err(dev->net, "asix_rx_fixup() Data Header synchronisation was lost, remaining %d\n",
                                   rx->remaining);
-                       if (rx->ax_skb) {
-                               kfree_skb(rx->ax_skb);
-                               rx->ax_skb = NULL;
-                               /* Discard the incomplete netdev Ethernet frame
-                                * and assume the Data header is at the start of
-                                * the current URB socket buffer.
-                                */
-                       }
-                       rx->remaining = 0;
+                       reset_asix_rx_fixup_info(rx);
                }
        }
 
@@ -139,11 +152,13 @@ int asix_rx_fixup_internal(struct usbnet *dev, struct sk_buff *skb,
                        if (size != ((~rx->header >> 16) & 0x7ff)) {
                                netdev_err(dev->net, "asix_rx_fixup() Bad Header Length 0x%x, offset %d\n",
                                           rx->header, offset);
+                               reset_asix_rx_fixup_info(rx);
                                return 0;
                        }
                        if (size > dev->net->mtu + ETH_HLEN + VLAN_HLEN) {
                                netdev_dbg(dev->net, "asix_rx_fixup() Bad RX Length %d\n",
                                           size);
+                               reset_asix_rx_fixup_info(rx);
                                return 0;
                        }
 
@@ -180,6 +195,7 @@ int asix_rx_fixup_internal(struct usbnet *dev, struct sk_buff *skb,
        if (skb->len != offset) {
                netdev_err(dev->net, "asix_rx_fixup() Bad SKB Length %d, %d\n",
                           skb->len, offset);
+               reset_asix_rx_fixup_info(rx);
                return 0;
        }