CVE-2022-44034: Analyzing the Linux Kernel Vulnerability in PCMCIA Device Handling - A Race Condition Between scr24x_open() and scr24x_remove()

In this long read post, we will delve into the details of a recent vulnerability discovered in the Linux kernel through version 6..6, identified as CVE-2022-44034. The security flaw is present in the drivers/char/pcmcia/scr24x_cs.c file and is related to a race condition and a subsequent use-after-free issue that might be exploited by a physically proximate attacker. To better understand this vulnerability, let's start by analyzing the affected code snippet, followed by an explanation of its implications, links to the original references, and attack scenarios.

Code Snippet

The vulnerable code resides in the scr24x_cs.c file, specifically in the scr24x_open() and scr24x_remove() functions. The race condition occurs if an attacker manages to remove a PCMCIA device while calling open(). Here's the relevant code snippet:

/* drivers/char/pcmcia/scr24x_cs.c */
/* ... */
static int scr24x_open(struct inode *inode, struct file *filp)
{
    struct pcmcia_device *link = (struct pcmcia_device *) imajor(filp->f_path.dentry->d_inode);
    scr24_private_t *dev;
    int ret;

    if (!pcmcia_dev_present(link))
        return -ENODEV;

    /* ... */
}

/* ... */

static void scr24x_remove(struct pcmcia_device *link)
{
    scr24_private_t *dev = link->priv;

    dev_dbg(&link->dev, "scr24x_remove\n");

    if (link->open)
        kfree(link->priv);
    
    /* ... */
}

Implications

The vulnerability in the code above presents an attack surface for a local attacker who has physical access to the targeted system. If the attacker removes a PCMCIA device while executing the open() system call, the race condition between scr24x_open() and scr24x_remove() can be triggered. This race condition may result in a use-after-free vulnerability, which could potentially lead to arbitrary code execution, denial-of-service attacks, or information leaks.

The discovery of CVE-2022-44034 can be attributed to the following references

1. Linux kernel Git commit addressing the issue: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c4ab3056a78dfa92d8d6fbc919c9ab775f947e7b
2. NVD vulnerability description: https://nvd.nist.gov/vuln/detail/CVE-2022-44034
3. Kernel.org Bugzilla report: https://bugzilla.kernel.org/show_bug.cgi?id=222731

Exploit Details

While there are currently no known public exploits for CVE-2022-44034, the vulnerability itself underscores the importance of securing both the software and physical layers of a system. Since this issue requires an attacker to have physical access to the targeted device, controlling and monitoring such access becomes a crucial aspect of an organization's security.

To mitigate this vulnerability, system administrators should ensure that they are running an up-to-date version of the Linux kernel, which includes patches for CVE-2022-44034. Additionally, organizations should implement strict controls over physical access to their systems and consider deploying intrusion detection and monitoring solutions to catch unauthorized activities in real-time.

Conclusion

CVE-2022-44034 is a notable race condition vulnerability in the Linux kernel, impacting versions up to 6..6. The issue lies in the scr24x_cs.c file, specifically in the interaction between the scr24x_open() and scr24x_remove() functions during the management of PCMCIA devices. While exploiting this vulnerability requires physical access to the targeted system, it underscores the importance of ensuring robust security at all layers of a computing environment. By updating to the latest Linux kernel and implementing strong physical security controls, organizations can significantly reduce their risk of being affected by vulnerabilities such as CVE-2022-44034.

Timeline

Published on: 10/30/2022 01:15:00 UTC
Last modified on: 11/01/2022 14:55:00 UTC