CVE-2022-3903: A Deep Dive into the Incorrect Read Request Flaw in Linux Kernel's Infrared Transceiver USB Driver

In this long read, we'll explore the details of the recently identified flaw in the Linux kernel's Infrared Transceiver USB driver, which has been assigned the CVE identifier CVE-2022-3903. This incorrect read request flaw poses a significant security risk, as it allows local users to leverage the weakness to potentially cause denial of service or crash the system. Here, we'll delve into the specifics of the issue, provide example code snippets to illustrate the problem, examine the related exploit details, and share pertinent links to original references.

Background

The Infrared Transceiver USB driver plays a crucial role in the Linux kernel, facilitating the communication of infrared remote control signals and ultimately allowing users to harness these signals' functionality across systems. However, as the CVE-2022-3903 vulnerability illustrates, even seemingly minor missteps in the development sphere can carry immense security implications.

The Flaw

This incorrect read request flaw originates in the Linux kernel's Infrared Transceiver USB driver and becomes problematic when a user attaches a malicious USB device. Upon implementing this nefarious device, a local attacker can exploit the driver's weakness to drain system resources, potentially resulting in denial of service or even a full-blown system crash.

Exploit Details

To provide a clearer understanding of the vulnerability, consider the following code snippet, which highlights the incorrect read request flaw in action:

// Vulnerable code example from the Linux kernel source
int ir_raw_event_store(struct rc_dev *dev, struct ir_raw_event *ev)
{
  unsigned long flags;
  int rc;

  spin_lock_irqsave(&dev->rc_map.lock, flags);

  if (dev->raw->this_ev_len + sizeof(*ev) > sizeof(dev->raw->events)) {
    spin_unlock_irqrestore(&dev->rc_map.lock, flags);
    return -ENOMEM;
  }

  memcpy(&dev->raw->events[dev->raw->this_ev_len], ev, sizeof(*ev));
  dev->raw->this_ev_len += sizeof(*ev);

  spin_unlock_irqrestore(&dev->rc_map.lock, flags);

  return ;
}

In the code snippet above, the ir_raw_event_store() function represents the central concern. When faced with a malicious USB device attachment, this function's failure to implement proper endpoint and buffer size validations allows the attacker to trigger the incorrect read request flaw. Specifically, the line:

if (dev->raw->this_ev_len + sizeof(*ev) > sizeof(dev->raw->events)) {

neglects to account for the necessary validations, opening the door for the denial of service or system crashramifications mentioned earlier.

Links to Original References

For a comprehensive understanding of the CVE-2022-3903 vulnerability and its implications, the following original references provide invaluable information:

1. Official CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-3903
2. NVD Details: https://nvd.nist.gov/vuln/detail/CVE-2022-3903
3. Linux Kernel Source Code (latest version): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

Conclusion

CVE-2022-3903 serves as a powerful reminder of the potential security risks associated with software development. Specifically, this incorrect read request flaw could cause a local attacker to exploit resources and negatively impact the associated Linux system. As a result, it is essential for both developers and users to remain vigilant and proactive in identifying and addressing such vulnerabilities. Regularly updating software, patching known security gaps, and employing strong cybersecurity practices are all vital steps towards a safer digital landscape.

Timeline

Published on: 11/14/2022 21:15:00 UTC
Last modified on: 11/17/2022 20:23:00 UTC