firewire: fix memory leak for payload of request subaction to IEC 61883-1 FCP region

In the Linux kernel, the following vulnerability has been resolved:

firewire: fix memory leak for payload of request subaction to IEC 61883-1 FCP region

This patch is fix for Linux kernel v2.6.33 or later.

For request subaction to IEC 61883-1 FCP region, Linux FireWire subsystem

have had an issue of use-after-free. The subsystem allows multiple

user space listeners to the region, while data of the payload was likely

released before the listeners execute read(2) to access to it for copying

to user space.

The issue was fixed by a commit 281e20323ab7 ("firewire: core: fix

use-after-free regression in FCP handler"). The object of payload is

duplicated in kernel space for each listener. When the listener executes

ioctl(2) with FW_CDEV_IOC_SEND_RESPONSE request, the object is going to

be released.

However, it causes memory leak since the commit relies on call of

release_request() in drivers/firewire/core-cdev.c. Against the

expectation, the function is never called due to the design of

release_client_resource(). The function delegates release task

to caller when called with non-NULL fourth argument. The implementation

of ioctl_send_response() is the case. It should release the object

explicitly.

This commit fixes the bug.