[media] lirc_dev: fix potential segfault

When opening or closing a lirc character device, the framework
provides to the user the possibility to keep track of opening or
closing of the device by calling two functions:

 - set_use_inc() when opening the device
 - set_use_dec() when closing the device

if those are not set by the lirc user, the system segfaults.
Check the pointer value before calling the above functions.

Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 4be447070fc44747de9d02f636c098d5bc206e31..a107ab6bcb882bca16371f2a164da53d0dd9b95f 100644 (file)
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -411,7 +411,10 @@ int lirc_unregister_driver(int minor)
                        ir->d.name, ir->d.minor);
                wake_up_interruptible(&ir->buf->wait_poll);
                mutex_lock(&ir->irctl_lock);
-               ir->d.set_use_dec(ir->d.data);
+
+               if (ir->d.set_use_dec)
+                       ir->d.set_use_dec(ir->d.data);
+
                module_put(cdev->owner);
                mutex_unlock(&ir->irctl_lock);
        } else {
@@ -469,7 +472,8 @@ int lirc_dev_fop_open(struct inode *inode, struct file *file)
        cdev = ir->cdev;
        if (try_module_get(cdev->owner)) {
                ir->open++;
-               retval = ir->d.set_use_inc(ir->d.data);
+               if (ir->d.set_use_inc)
+                       retval = ir->d.set_use_inc(ir->d.data);
 
                if (retval) {
                        module_put(cdev->owner);
@@ -510,7 +514,8 @@ int lirc_dev_fop_close(struct inode *inode, struct file *file)
 
        ir->open--;
        if (ir->attached) {
-               ir->d.set_use_dec(ir->d.data);
+               if (ir->d.set_use_dec)
+                       ir->d.set_use_dec(ir->d.data);
                module_put(cdev->owner);
        } else {
                lirc_irctl_cleanup(ir);