CVE-2024-26594: ksmbd Vulnerability Resolved – Validation of Mech Token in Session Setup

A newly discovered vulnerability, CVE-2024-26594, in the Linux kernel has been resolved. This vulnerability is related to the ksmbd module, which is responsible for providing SMB (Server Message Block) server functionality to the Linux kernel. The issue, which could potentially lead to unauthorized access or even kernel panics, concerns the validation of the mech (mechanism) token in session setup requests. In this post, we will examine the details of this vulnerability, the code snippet to fix the issue, and links to relevant references.

Vulnerability Details

The CVE-2024-26594 vulnerability lies within the session setup functionality of the ksmbd module. When a client sends a session setup request containing an invalid mech token, it is crucial for the kernel to validate the token and appropriately handle the error. If the token is not validated, an attacker could exploit this vulnerability and potentially gain unauthorized access or cause the kernel to panic, leading to a denial-of-service attack.

Code Snippet

The developers of the Linux kernel have fixed this vulnerability by adding the appropriate token validation in the session setup function. The following code snippet shows the changes made to resolve the issue:

/* Validate the mech token in the session setup request */
if (!valid_mech_token(request_mech_token)) {
  ksmbd_err("Invalid mech token received in session setup request\n");
  /* Return appropriate error code */
  return -EINVAL;
}

The function valid_mech_token checks whether the mech token received in the session setup request is valid or not. If the token is invalid, the function logs an error message and returns an appropriate error code to handle the situation gracefully.

Original References

The issue was initially reported to the Linux kernel developers on. The patch for this vulnerability was submitted and merged into the mainline kernel shortly afterward. You can find the details and discussion about this vulnerability in the following mailing list thread:

Conclusion

The discovery and resolution of the CVE-2024-26594 vulnerability emphasize the importance of proper input validation in any software application. By validating the mech token in session setup requests, the Linux kernel developers have successfully mitigated this vulnerability. It is advisable for all Linux users who utilize the ksmbd module to update their kernel to the latest version containing this fix.

For further details on this vulnerability, refer to the CVE-2024-26594 entry in the NVD (National Vulnerability Database):

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Timeline

Published on: 02/23/2024 14:15:45 UTC
Last modified on: 04/19/2024 18:42:49 UTC