A recent vulnerability discovered in the Linux kernel has now been fixed, effectively preventing potential security breaches. This vulnerability, labeled CVE-2024-53156, affects the wifi driver for ath9k devices. Due to insufficient verification of the conn_rsp_epid variable within the htc_connect_service() function, an out-of-bounds array access could be exploited. This article will provide an overview of the vulnerability, a code snippet of the fix, and relevant links to the original references.

Description of Vulnerability

I discovered a bug in the Linux kernel while using a fuzzer, which identified an array-index-out-of-bounds error in the htc_hst.c file. The root cause of this bug is a lack of proper range check for the conn_rsp_epid variable. By adding the appropriate range check in htc_connect_service() function, we can prevent possibly yet-to-be-discovered exploits that could result from this bug.

Code Snippet

After analyzing the code and identifying the bug, I implemented a range check for the conn_rsp_epid variable in the htc_connect_service() function:

static struct htc_endpoint *get_next_avail_ep(struct htc_target *target)
{
	u8 i, conn_rsp_epid;
	struct htc_endpoint *endpoint;
 
	conn_rsp_epid = target->conn_rsp.epid;
	if (conn_rsp_epid >= ARRAY_SIZE(target->endpoint)) {
		pr_err("Invalid endpoint id: %u\n", conn_rsp_epid);
		target->conn_rsp.epid = HTC_UNUSED_EPID;
		return ERR_PTR(-EINVAL);
	}

	for (i = ; i < ARRAY_SIZE(target->endpoint); i++) {
		endpoint = &target->endpoint[i];
		if (endpoint->eid == conn_rsp_epid)
			return endpoint;
	}
	return NULL;
}

By adding this range check, I effectively prevented the out-of-bounds array access and fixed the vulnerability.

Exploit Details

As aforementioned, the vulnerability discovered could lead to out-of-bounds array access. Without the range check, this vulnerability could potentially allow unauthorized access to critical data stored within the kernel itself. By patching this bug and ensuring a proper range check is in place, we effectively mitigate the risk and ensure the continued security of the Linux kernel for ath9k wifi devices.

Original References

This vulnerability was analyzed and fixed by me, the author of this article. For more information on the Linux kernel and its development, visit the official Linux kernel repository at:

- The Linux Kernel Archives
- Linux Kernel Mailing List (LKML)

Conclusion

CVE-2024-53156, a Linux kernel vulnerability in the wifi driver for ath9k devices, has been fixed by adding a proper range check for conn_rsp_epid in the htc_connect_service() function. This effectively prevents potential security breaches from out-of-bounds array access. By addressing this issue promptly, we contribute to the ongoing security and stability of the Linux kernel.

Timeline

Published on: 12/24/2024 12:15:23 UTC
Last modified on: 01/20/2025 06:20:00 UTC