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

On Sat, Oct 29, 2011 at 11:36 AM, Arend van Spriel [off-list ref] wrote:

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

quoted

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.

No, this one is definitely needed. Its devices_lock, not
device->readers_lock! And devices_lock is locked before so we need to
unlock it if we return in this branch.

quoted

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

Regards
David
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