CVE-2022-48821 misc: fastrpc: avoid double fput() on failed usercopy
A use-after-free vulnerability in the Linux kernel's fastrpc driver allows local attackers to potentially execute code or escalate privileges via a failed usercopy operation.
- 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-2022-48821?
CVE-2022-48821 is a high-severity use after free vulnerability in Linux kernel, published on 16 Jul 2024. 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:
misc: fastrpc: avoid double fput() on failed usercopy
If the copy back to userland fails for the FASTRPC_IOCTL_ALLOC_DMA_BUFF ioctl(), we shouldn't assume that 'buf->dmabuf' is still valid. In fact, dma_buf_fd() called fd_install() before, i.e. "consumed" one reference, leaving us with none.
Calling dma_buf_put() will therefore put a reference we no longer own, leading to a valid file descritor table entry for an already released 'file' object which is a straight use-after-free.
Simply avoid calling dma_buf_put() and rely on the process exit code to do the necessary cleanup, if needed, i.e. if the file descriptor is still valid.
Weakness: CWE-416
Which versions are affected by CVE-2022-48821?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-48821?
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-2022-48821 being exploited?
There is no known exploitation of CVE-2022-48821 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-48821, GHSA-h4q9-9fhm-542g, UBUNTU-CVE-2022-48821.