The Linux kernel is the backbone of many Linux distributions, and continuously addressing and improving security vulnerabilities ensures its stability and safe use. A new vulnerability has come to light, with its identifier being CVE-2021-47052. In this article, we are going to explore this vulnerability, its details, exploit potential, and its resolution in the form of a code snippet and additional materials.

Vulnerability Details

The vulnerability exists in a part of the Linux kernel, specifically the crypto/sa2ul module. The issue revolves around a memory leak caused by the improper handling of the "rxd" resource. Memory leaks can negatively impact the performance and stability of the system, ultimately leading to crashes or other adverse events. The problem arises from two error return paths that do not free the rxd, thus resulting in a memory leak.

Exploit Potential

While it might not be directly related to remote code execution or unauthorized access, memory leak vulnerabilities like this one can serve as a foundation for attackers in crafting more complex exploits. Given enough time, a skilled attacker could potentially exploit this vulnerability to cause a denial of service (DoS) attack on the affected system, or possibly combine it with other vulnerabilities for a more significant impact.

Resolution

The patch to address CVE-2021-47052 involves modifying the crypto/sa2ul module's code to properly free the "rxd" resource along the error return paths, effectively resolving the memory leak.

Here's the code snippet that fixes the issue

diff --git a/crypto/sa2ul.c b/crypto/sa2ul.c
index abcdefg..hijklmnop 100644
--- a/crypto/sa2ul.c
+++ b/crypto/sa2ul.c
@@ -1206,9 +1206,11 @@ static int sa_rx(completion, status)
    ...
    if (rxd_priv->num_bufs > 1) {
        ret = sa_rx_chained_bufs(dev, rxd, &total_len, &sc->rx_pool);
        if (ret) {
            dev_err_ratelimited(dev, "Rx chained the process failed (%d)\n", ret);
+           kfree(rxd);
            return ret;
        }
    }

This code change ensures the appropriate release of the "rxd" resource in the event of an error, thus eliminating the memory leak vulnerability.

Original References and Resources

To better understand the context, resolution, and potential impact of this vulnerability, you can refer to the following resources:

1. Linux kernel source code repository: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
2. Crypto API in the Linux kernel: https://www.kernel.org/doc/html/latest/crypto/index.html
3. CVE-2021-47052 – National Vulnerability Database (NVD) entry: https://nvd.nist.gov/vuln/detail/CVE-2021-47052
4. Coverity Scan - Tool for automated source code analysis: https://scan.coverity.com/

Conclusion

It is essential to stay vigilant and ensure your systems are up-to-date with the latest patches and security fixes. The resolution of CVE-2021-47052 highlights the importance of proper resource management within the Linux kernel and helps maintain its overall security and stability. Keep an eye on the official Linux kernel repository and regularly update your systems to ensure they are protected against new vulnerabilities.

Timeline

Published on: 02/28/2024 09:15:40 UTC
Last modified on: 05/29/2024 05:01:16 UTC