1 files changed, 45 insertions, 18 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 2bed83caacb1..9720e699f472 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -806,6 +806,48 @@ static int usb_string_sub(struct usb_device *dev, unsigned int langid,
         return rc;
 }
 
+static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf)
+{
+        int err;
+
+        if (dev->have_langid)
+                return 0;
+
+        if (dev->string_langid < 0)
+                return -EPIPE;
+
+        err = usb_string_sub(dev, 0, 0, tbuf);
+
+        /* If the string was reported but is malformed, default to english
+         * (0x0409) */
+        if (err == -ENODATA || (err > 0 && err < 4)) {
+                dev->string_langid = 0x0409;
+                dev->have_langid = 1;
+                dev_err(&dev->dev,
+                        "string descriptor 0 malformed (err = %d), "
+                        "defaulting to 0x%04x\n",
+                                err, dev->string_langid);
+                return 0;
+        }
+
+        /* In case of all other errors, we assume the device is not able to
+         * deal with strings at all. Set string_langid to -1 in order to
+         * prevent any string to be retrieved from the device */
+        if (err < 0) {
+                dev_err(&dev->dev, "string descriptor 0 read error: %d\n",
+                                        err);
+                dev->string_langid = -1;
+                return -EPIPE;
+        }
+
+        /* always use the first langid listed */
+        dev->string_langid = tbuf[2] | (tbuf[3] << 8);
+        dev->have_langid = 1;
+        dev_dbg(&dev->dev, "default language 0x%04x\n",
+                                dev->string_langid);
+        return 0;
+}
+
 /**
  * usb_string - returns UTF-8 version of a string descriptor
  * @dev: the device whose string descriptor is being retrieved
@@ -837,24 +879,9 @@ int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
         if (!tbuf)
                 return -ENOMEM;
 
-        /* get langid for strings if it's not yet known */
-        if (!dev->have_langid) {
-                err = usb_string_sub(dev, 0, 0, tbuf);
-                if (err < 0) {
-                        dev_err(&dev->dev,
-                                "string descriptor 0 read error: %d\n",
-                                err);
-                } else if (err < 4) {
-                        dev_err(&dev->dev, "string descriptor 0 too short\n");
-                } else {
-                        dev->string_langid = tbuf[2] | (tbuf[3] << 8);
-                        /* always use the first langid listed */
-                        dev_dbg(&dev->dev, "default language 0x%04x\n",
-                                dev->string_langid);
-                }
-
-                dev->have_langid = 1;
-        }
+        err = usb_get_langid(dev, tbuf);
+        if (err < 0)
+                goto errout;
 
         err = usb_string_sub(dev, dev->string_langid, index, tbuf);
         if (err < 0)