CVE-2022-49755: usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait
First published: Thu Mar 27 2025(Updated: )
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).
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=2.6.35<4.14.305 | |
| Linux Kernel | >=4.15<4.19.272 | |
| Linux Kernel | >=4.20<5.4.231 | |
| Linux Kernel | >=5.5<5.10.166 | |
| Linux Kernel | >=5.11<5.15.91 | |
| Linux Kernel | >=5.16<6.1.9 | |
| Linux Kernel | =6.2-rc1 | |
| Linux Kernel | =6.2-rc2 | |
| Linux Kernel | =6.2-rc3 | |
| Linux Kernel | =6.2-rc4 |
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Reference Links
- https://git.kernel.org/stable/c/facf353c9e8d7885b686d9a4b173d4e0af6441d2
- https://git.kernel.org/stable/c/e9036e951f93fb8d7b5e9d6e2c7f94a4da312ae4
- https://git.kernel.org/stable/c/a8d40942df074f4ebcb9bd3413596d92f323b064
- https://git.kernel.org/stable/c/6dd9ea05534f323668db94fcc2726c7a84547e78
- https://git.kernel.org/stable/c/ae8e136bcaae96163b5821984de1036efc9abb1a
- https://git.kernel.org/stable/c/6aee197b7fbcd61596a78b47d553f2f99111f217
- https://git.kernel.org/stable/c/6a19da111057f69214b97c62fb0ac59023970850
Frequently Asked Questions
What is the severity of CVE-2022-49755?
CVE-2022-49755 is classified as a high-severity vulnerability due to the potential for race conditions affecting the USB gadget functionality in the Linux kernel.
How do I fix CVE-2022-49755?
To fix CVE-2022-49755, update the Linux kernel to the latest version where the vulnerability has been patched.
Which versions of Linux Kernel are affected by CVE-2022-49755?
CVE-2022-49755 affects multiple versions of the Linux kernel prior to the release that includes the fix.
What are the risks associated with CVE-2022-49755?
The risks associated with CVE-2022-49755 include potential denial-of-service attacks or unintended behaviors in USB communication.
Is CVE-2022-49755 being actively exploited?
As of the latest updates, there is no public indication that CVE-2022-49755 is being actively exploited in the wild.
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