CVE-2022-49755

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait<br /> <br /> While performing fast composition switch, there is a possibility that the<br /> process of ffs_ep0_write/ffs_ep0_read get into a race condition<br /> due to ep0req being freed up from functionfs_unbind.<br /> <br /> Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait<br /> by taking a lock &amp;ffs-&gt;ev.waitq.lock. However, the functionfs_unbind isn&amp;#39;t<br /> bounded so it can go ahead and mark the ep0req to NULL, and since there<br /> is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free.<br /> <br /> Fix this by making a serialized execution between the two functions using<br /> a mutex_lock(ffs-&gt;mutex).