isight_firmware: Avoid crash on loading invalid firmware

Different tools generate slightly different formats of the isight firmware. Ensure that the firmware buffer is not overrun, while still ensuring that the correct amount of data is written if trailing data is present. Signed-off-by: Matthew Garrett <[email protected]> Report-by: Justin Mattock <[email protected]> Tested-by: Justin Mattock <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
josf · Jun 12, 2008 · 62b5884 · 62b5884
1 parent 6460a26
commit 62b5884
Showing 1 changed file with 16 additions and 7 deletions.
diff --git a/drivers/usb/misc/isight_firmware.c b/drivers/usb/misc/isight_firmware.c
@@ -39,9 +39,12 @@ static int isight_firmware_load(struct usb_interface *intf,
 	struct usb_device *dev = interface_to_usbdev(intf);
 	int llen, len, req, ret = 0;
 	const struct firmware *firmware;
-	unsigned char *buf;
+	unsigned char *buf = kmalloc(50, GFP_KERNEL);
 	unsigned char data[4];
-	char *ptr;
+	u8 *ptr;
+
+	if (!buf)
+		return -ENOMEM;
 
 	if (request_firmware(&firmware, "isight.fw", &dev->dev) != 0) {
 		printk(KERN_ERR "Unable to load isight firmware\n");
@@ -59,7 +62,7 @@ static int isight_firmware_load(struct usb_interface *intf,
 		goto out;
 	}
 
-	while (1) {
+	while (ptr+4 <= firmware->data+firmware->size) {
 		memcpy(data, ptr, 4);
 		len = (data[0] << 8 | data[1]);
 		req = (data[2] << 8 | data[3]);
@@ -71,10 +74,14 @@ static int isight_firmware_load(struct usb_interface *intf,
 			continue;
 
 		for (; len > 0; req += 50) {
-			llen = len > 50 ? 50 : len;
+			llen = min(len, 50);
 			len -= llen;
-
-			buf = kmalloc(llen, GFP_KERNEL);
+			if (ptr+llen > firmware->data+firmware->size) {
+				printk(KERN_ERR
+				       "Malformed isight firmware");
+				ret = -ENODEV;
+				goto out;
+			}
 			memcpy(buf, ptr, llen);
 
 			ptr += llen;
@@ -89,16 +96,18 @@ static int isight_firmware_load(struct usb_interface *intf,
 				goto out;
 			}
 
-			kfree(buf);
 		}
 	}
+
 	if (usb_control_msg
 	    (dev, usb_sndctrlpipe(dev, 0), 0xa0, 0x40, 0xe600, 0, "\0", 1,
 	     300) != 1) {
 		printk(KERN_ERR "isight firmware loading completion failed\n");
 		ret = -ENODEV;
 	}
+
 out:
+	kfree(buf);
 	release_firmware(firmware);
 	return ret;
 }