USB: serial: io_edgeport: fix descriptor error handling

commit 3c0e25d883d06a1fbd1ad35257e8abaa57befb37 upstream.

Make sure to detect short control-message transfers and log an error
when reading incomplete manufacturer and boot descriptors.

Note that the default all-zero descriptors will now be used after a
short transfer is detected instead of partially initialised ones.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index e5795c0..d4109f2 100644 (file)
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -2263,8 +2263,7 @@ static int rom_write(struct usb_serial *serial, __u16 extAddr, __u16 addr,
  * rom_read
  *     reads a number of bytes from the Edgeport device starting at the given
  *     address.
- *     If successful returns the number of bytes read, otherwise it returns
- *     a negative error number of the problem.
+ *     Returns zero on success or a negative error number.
  ****************************************************************************/
 static int rom_read(struct usb_serial *serial, __u16 extAddr,
                                        __u16 addr, __u16 length, __u8 *data)
@@ -2296,12 +2295,17 @@ static int rom_read(struct usb_serial *serial, __u16 extAddr,
                                        USB_REQUEST_ION_READ_ROM,
                                        0xC0, addr, extAddr, transfer_buffer,
                                        current_length, 300);
-               if (result < 0)
+               if (result < current_length) {
+                       if (result >= 0)
+                               result = -EIO;
                        break;
+               }
                memcpy(data, transfer_buffer, current_length);
                length -= current_length;
                addr += current_length;
                data += current_length;
+
+               result = 0;
        }
 
        kfree(transfer_buffer);
@@ -2772,10 +2776,11 @@ static void get_manufacturing_desc(struct edgeport_serial *edge_serial)
                                EDGE_MANUF_DESC_LEN,
                                (__u8 *)(&edge_serial->manuf_descriptor));
 
-       if (response < 1)
+       if (response < 0) {
                dev_err(&edge_serial->serial->dev->dev,
-                       "error in getting manufacturer descriptor\n");
-       else {
+                       "error in getting manufacturer descriptor: %d\n",
+                       response);
+       } else {
                char string[30];
                dbg("**Manufacturer Descriptor");
                dbg("  RomSize:        %dK",
@@ -2831,10 +2836,11 @@ static void get_boot_desc(struct edgeport_serial *edge_serial)
                                EDGE_BOOT_DESC_LEN,
                                (__u8 *)(&edge_serial->boot_descriptor));
 
-       if (response < 1)
+       if (response < 0) {
                dev_err(&edge_serial->serial->dev->dev,
-                               "error in getting boot descriptor\n");
-       else {
+                       "error in getting boot descriptor: %d\n",
+                       response);
+       } else {
                dbg("**Boot Descriptor:");
                dbg("  BootCodeLength: %d",
                    le16_to_cpu(edge_serial->boot_descriptor.BootCodeLength));