Re: [PATCH 3/5] drivers/hid/hid-roccat.c: eliminate a null pointer dereference

On 10/29/2011 08:24 AM, Dan Carpenter wrote:

On Sat, Oct 29, 2011 at 01:58:15AM +0200, Julia Lawall wrote:

quoted

diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c
index 2596321..36a28b8 100644
--- a/drivers/hid/hid-roccat.c
+++ b/drivers/hid/hid-roccat.c

@@ -163,14 +163,15 @@ static int roccat_open(struct inode *inode, struct file *file)
 
 	device = devices[minor];
 
-	mutex_lock(&device->readers_lock);
-
 	if (!device) {
 		pr_emerg("roccat device with minor %d doesn't exist\n", minor);
-		error = -ENODEV;
-		goto exit_err;
+		kfree(reader);
+		mutex_lock(&devices_lock);

Typo.  mutex_unlock() instead of mutex_lock().

This is no typo, but simply wrong. Remove the mutex_lock() as we are
leaving the function here in error flow.

quoted

+		return -ENODEV;
 	}
 
+	mutex_lock(&device->readers_lock);
+
 	if (!device->open++) {
 		/* power on device on adding first reader */
 		error = hid_hw_power(device->hid, PM_HINT_FULLON);

regards,
dan carpenter

Gr. AvS