CVE-2022-49755 usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait
A race condition in the Linux kernel USB gadget driver allows a use-after-free, potentially enabling code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-49755?
CVE-2022-49755 is a high-severity use after free vulnerability in Linux kernel, published on 27 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait
While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind.
Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free.
Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex).
Weakness: CWE-416
Which versions are affected by CVE-2022-49755?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49755?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2022-49755 being exploited?
There is no known exploitation of CVE-2022-49755 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49755, GHSA-qc5x-h4r4-86f3, UBUNTU-CVE-2022-49755.