ipmi: ipmi_devintf: compat_ioctl method fails to take ipmi_mutex

When a 32 bit version of ipmitool is used on a 64 bit kernel, the
ipmi_devintf code fails to correctly acquire ipmi_mutex.  This results in
incomplete data being retrieved in some cases, or other possible failures.
Add a wrapper around compat_ipmi_ioctl() to take ipmi_mutex to fix this.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/ipmi/ipmi_devintf.c

@@ -837,13 +837,25 @@ static long compat_ipmi_ioctl(struct file *filep, unsigned int cmd,
 		return ipmi_ioctl(filep, cmd, arg);
 	}
 }
+
+static long unlocked_compat_ipmi_ioctl(struct file *filep, unsigned int cmd,
+				       unsigned long arg)
+{
+	int ret;
+
+	mutex_lock(&ipmi_mutex);
+	ret = compat_ipmi_ioctl(filep, cmd, arg);
+	mutex_unlock(&ipmi_mutex);
+
+	return ret;
+}
 #endif
 
 static const struct file_operations ipmi_fops = {
 	.owner		= THIS_MODULE,
 	.unlocked_ioctl	= ipmi_unlocked_ioctl,
 #ifdef CONFIG_COMPAT
-	.compat_ioctl   = compat_ipmi_ioctl,
+	.compat_ioctl   = unlocked_compat_ipmi_ioctl,
 #endif
 	.open		= ipmi_open,
 	.release	= ipmi_release,