CVE-2024-26952: Understanding and Mitigating the ksmbd Out-of-Bounds Vulnerability in the Linux Kernel

Recently, a vulnerability (CVE-2024-26952) was identified and resolved in the Linux kernel. The issue can potentially lead to out-of-bounds access when buffer offset fields within certain requests are found to be invalid. This article offers a comprehensive understanding of the issue, code snippet, links to original references, and details on how to exploit and mitigate the vulnerability.

CVE-2024-26952 Details

In the Linux kernel, the ksmbd module has been found to have a potential out-of-bounds vulnerability when buffer offset fields of specific requests are invalid. To resolve this issue, a patch has been proposed to set the minimum value of the buffer offset field, thereby validating the buffer length and preventing potential exploitation.

The patch for this vulnerability can be found in the following code snippet

- #define KSMBD_REQ_MINIMUM_SIZE		(sizeof(struct ksmbd_inst_hdr) + sizeof(struct ksmbd_inbuf_hdr) + sizeof(WCHAR))
+ #define KSMBD_REQ_MINIMUM_SIZE		(sizeof(struct ksmbd_inst_hdr) + sizeof(struct ksmbd_inbuf_hdr) + sizeof(WCHAR) + sizeof(struct ksmbd_buffer_offset))

By changing the defined minimum size in the patch, the buffer offset field is correctly validated, and the potential for out-of-bounds access is reduced.

The issue was initially reported in the following mailing list thread

* OSS-Security: ksmbd: fix potencial out-of-bounds when buffer offset is invalid

Exploit Details

An attacker could potentially exploit the vulnerability by crafting specific requests with invalid buffer offset fields, which may then result in out-of-bounds access and possibly lead to information disclosure, service downtime, or even arbitrary code execution.

Mitigation

The best way to mitigate this vulnerability is to apply the appropriate patch and ensure that your Linux kernel is updated to the latest stable version. Additionally, enable automatic security updates for your system to minimize the window of opportunity for attackers to exploit any vulnerabilities.

Conclusion

CVE-2024-26952 is a recently discovered vulnerability affecting the ksmbd module of the Linux kernel. With the potential for out-of-bounds access resulting from invalid buffer offset fields, taking appropriate steps to understand, patch, and mitigate the vulnerability is crucial for maintaining the security and stability of your system. By applying the patch and enabling automatic updates, you can ensure that your Linux kernel remains protected against potential exploitation.

Timeline

Published on: 05/01/2024 06:15:11 UTC
Last modified on: 07/03/2024 01:50:06 UTC