IB/ipath: Only allow complete writes to flash

Don't allow a write to the eeprom from ipathfs unless the write is exactly
128 bytes and starts at offset 0.

Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ipath/ipath_fs.c

@@ -356,19 +356,16 @@ static ssize_t flash_write(struct file *file, const char __user *buf,
 
 	pos = *ppos;
 
-	if ( pos < 0) {
+	if (pos != 0) {
 		ret = -EINVAL;
 		goto bail;
 	}
 
-	if (pos >= sizeof(struct ipath_flash)) {
-		ret = 0;
+	if (count != sizeof(struct ipath_flash)) {
+		ret = -EINVAL;
 		goto bail;
 	}
 
-	if (count > sizeof(struct ipath_flash) - pos)
-		count = sizeof(struct ipath_flash) - pos;
-
 	tmp = kmalloc(count, GFP_KERNEL);
 	if (!tmp) {
 		ret = -ENOMEM;