CVE-2024-26811 – ksmbd: Validate Payload Size in IPC Response to Prevent Memory Overrun and Slab-Out-Of-Bounds Issues in the Linux Kernel

In the ever-evolving world of cybersecurity, vulnerabilities are discovered and resolved regularly to ensure the safety and stability of systems. One such vulnerability identified recently in the Linux kernel is related to ksmbd, and it has been logged under the identifier CVE-2024-26811. To provide you with an in-depth understanding of this issue, we'll discuss the vulnerability, code snippets, original references, and exploit details.

Vulnerability Details

The CVE-2024-26811 vulnerability involves a lack of payload size validation in the IPC (Inter-Process Communication) response of kernel server (ksmbd). This issue can arise when malicious ksmbd-tools are installed, leading ksmbd.mountd to return an invalid IPC response to the ksmbd kernel server.

Such a situation can result in memory overrun errors or slab-out-of-bounds issues. Therefore, it is crucial to validate the payload sizes of IPC responses from ksmbd.mountd to prevent these problems.

Code Snippet

A patch has been released to resolve this vulnerability. Here's a code snippet of the solution added to validate payload size in ipc response:

int ksmbd_ipc_ksmbd_register_ch(struct ksmbd_ipc_msg *msg)
{
	struct ksmbd_mount_path *data;
	size_t payload_size = ksmbd_ipc_msg_payload_size(msg);

	if (payload_size < sizeof(struct ksmbd_mount_path)) {
		ksmbd_err("Invalid payload size %zu\n", payload_size);
		return -EINVAL;
	}

	data = ksmbd_ipc_msg_payload(msg);
	if (payload_size < sizeof(struct ksmbd_mount_path) +
	    data->mntpathlen + data->sharenamelen) {
		ksmbd_err("Invalid payload size for ksmbd_share(%zu)\n", payload_size);
		return -EINVAL;
	}
	...
}

This patch validates the three IPC responses that contain payloads and ensure a proper size check to avoid potential memory overrun or slab-out-of-bounds issues.

For more information about CVE-2024-26811 and the patch, you can consult the following references

- CVE record: CVE-2024-26811
- Linux kernel mailing list patch discussion: [PATCH net] ksmbd: validate payload size of ipc response](https://lore.kernel.org/patchwork/patch/1594091/)
- Commit details in ksmbd project GitHub repository: Commit

Exploit Details

An attacker can exploit CVE-2024-26811 by deploying malicious ksmbd-tools, leading to ksmbd.mountd returning invalid IPC responses to the ksmbd kernel server. This allows the attacker to cause memory overrun or slab-out-of-bound issues, potentially leading to a crash or corruption of the targeted Linux system.

It's essential to apply the patch mentioned above and update to the latest ksmbd version to avoid any potential exploits.

In conclusion, the CVE-2024-26811 vulnerability can have significant effects on the stability and security of a Linux system. Therefore, system administrators should ensure payload size validation for the ksmbd kernel server's IPC responses to prevent memory overrun and slab-out-of-bounds issues and keep their systems up-to-date and secure.

Timeline

Published on: 04/08/2024 10:15:08 UTC
Last modified on: 12/19/2024 08:47:56 UTC