CVE-2023-52656 - Linux Kernel io_uring vulnerability resolved by dropping SCM

A vulnerability has been identified and resolved in the Linux kernel's io_uring subsystem. Previously, there was support for passing io_uring file descriptors (often abbreviated as "fds") over SCM_RIGHTS. However, this support has been dropped and as a result, the associated dead code has been removed to mitigate any potential security risks.

Details

io_uring is a subsystem in the Linux kernel that provides an efficient and scalable mechanism for asynchronous input/output operations, making it an essential component of the Linux operating system. The vulnerability (CVE-2023-52656) identified in the Linux kernel dealt with the use of SCM_RIGHTS to send and receive file descriptors for io_uring.

When investigating this issue, it was discovered that this code was no longer being used after support for passing io_uring fds over SCM_RIGHTS was dropped. This dead code presented a potential security vulnerability and needed to be removed.

Code Snippet

To address this vulnerability, the following code related to SCM_RIGHTS has been removed from the Linux kernel. The code snippet below showcases the change:

- #ifdef CONFIG_PROC_FS
- /*
- * This will usually get called for SCM_RIGHTS passing of io_uring
- * instances.
- */
- static int io_uring_show_fdinfo(struct seq_file *m, struct file *f)
- {
- struct io_ring_ctx *ctx = f->private_data;
- ...
- }
- #endif

By removing the above code, the Linux kernel is no longer vulnerable to any potential security issues related to the use of SCM_RIGHTS for passing io_uring fds.

Links to Original References

- Linux kernel source code changes: Commit on Linux kernel git repository
- Explanation of the change and removal of SCM_RIGHTS support: io_uring documentation on kernel.org

Exploit Details

Although there has not been an exploit developed specifically for this vulnerability, its discovery prompted the removal of this dead code to minimize any potential risks. This issue highlights the importance of continuous monitoring and security auditing of kernel code to identify and address potential vulnerabilities proactively.

Conclusion

In conclusion, CVE-2023-52656 has been resolved by dropping support for passing io_uring fds over SCM_RIGHTS and removing the associated dead code. This change eliminates any potential security risks and improves the overall stability of the Linux kernel. By staying informed about releases and security issues, users of the Linux kernel can help ensure their systems remain protected against emerging threats.

Timeline

Published on: 05/14/2024 14:23:13 UTC
Last modified on: 06/25/2024 23:15:23 UTC