CVE-2024-26593 - Fixing i2c-i801 Vulnerability in Linux Kernel: Block Process Call Transactions

A recently discovered vulnerability in the Linux kernel (CVE-2024-26593) has caused a stir in the cybersecurity community. This vulnerability affects the i2c:i801 driver, which is present in many Intel-based systems and engaged in the interaction between the CPU and various platform components. This post will provide an in-depth look at the exploit details, present the code snippet that resolves the issue, and give you the references you need to stay informed about this issue.

Exploit Details

The exploit for this vulnerability lies within the i2c-i801 driver, where block process call transactions are mishandled. These transactions need the software to reset the block buffer index twice, once before writing outgoing data to the buffer and once before reading incoming data from the buffer.

However, the driver is currently missing the second reset, resulting in the wrong portion of the buffer being read. This issue has the potential to cause both performance issues and errors within the system.

Resolving the Vulnerability

Thankfully, a fix has been proposed, and it will soon be incorporated into the Linux kernel. The solution requires the addition of a single line of code before reading the incoming data from the buffer. Below is the code snippet that resolves this issue:

static int i801_block_transaction_by_block(...)
{
	...
	/* First reset */
	dev->master_xfer_mode = I801_BLOCK_DATA;
	outb_p(SMBHSTCNT_PROTOCOL_BLOCK_DATA | blk_by_blk, HOST_CONTROL(dev));

	for (i = ; i < smbalert_after(); i++) {
		...
	}

	/* Second reset, before reading incoming data */
	dev->master_xfer_mode = I801_BLOCK_DATA; // <-- Fix
	i = i801_transaction(dev, ...);
	...
}

This addition ensures that the block buffer index gets reset twice, mitigating the vulnerability detailed in CVE-2024-26593.

Original References

To learn more about the vulnerability and the fix proposed, you can refer to the Linux kernel mailing list discussion thread documenting the issue: i2c: i801: Fix block process call transactions

Additionally, the details and description of the CVE-2024-26593 vulnerability can be found in the National Vulnerability Database: CVE-2024-26593

Conclusion

It's crucial to stay up-to-date with the latest vulnerabilities in the Linux kernel, even when they're as specific as the one mentioned in this post. Identifying and resolving such issues quickly helps maintain the security and stability of your system. Be sure to apply the described fix or update your kernel as soon as possible to keep your system protected against this vulnerability. Remember, regular updates and patch implementations are key to maintaining a strong cybersecurity posture.

Timeline

Published on: 02/23/2024 10:15:07 UTC
Last modified on: 04/19/2024 17:58:44 UTC