A newly discovered vulnerability, CVE-2024-0607, has been found in the Netfilter subsystem of the Linux kernel. Netfilter is an important part of the Linux kernel which is responsible for managing network traffic filtering, forwarding and modifying activities. Specifically, this particular vulnerability is present in the nft_byteorder_eval() function. This function has a critical flaw that can lead to denial of service attacks or potentially disrupt the proper functioning of Netfilter.

Exploit Details

The flaw in the nft_byteorder_eval() function is a result of improper handling of a loop when it is writing data to the dst array. In each iteration of the loop, 8 bytes are written to the dst array. However, the dst array itself is an array of u32, meaning that it can only hold 4 bytes per element. Consequently, every iteration overwrites part of the previous element, which corrupts the entire u32 array.

Here is the code snippet showcasing the vulnerability

void nft_byteorder_eval(const struct nft_expr *expr, struct nft_regs *regs, const struct nft_pktinfo *pkt) {
    unsigned int len = NFT_BYTEORDER_SIZE(instead->ops); // Example: len = 8
    const u32 *src = &regs->data[net->sreg];
    u32 *dst = &regs->data[net->dreg];

    for (; len; len--) {
        *dst++ = src[]; // Writes 8 bytes in a u32 array element (size = 4 bytes)
        src++;
    }
}

Such improper handling of the loop causes data corruption in the dst array of u32 elements. A local user with enough privileges could exploit this vulnerability to cause denial of service attacks or potentially break the NetFilter functionality, leading to widespread issues with the Linux systems affected by this flaw.

Mitigation and Original References

To mitigate this issue, it is recommended to follow security best practices such as keeping the Linux kernel and system up-to-date, regularly reviewing access controls, and monitoring for any suspicious activities on your systems. In addition, kernel developers are also expected to provide an official patch to fix the vulnerability.

For further details and updates on this security flaw, you can refer to the original references below:

1. NVD - CVE-2024-0607
2. Linux Kernel Netfilter Subsystem
3. Kernel Mailing List - Patch Submission (Expected link; patch not yet submitted)

Conclusion

CVE-2024-0607 is a critical vulnerability in the Linux kernel's Netfilter subsystem that affects the nft_byteorder_eval() function. As such, it is essential for users and administrators to be aware of this flaw, its potential consequences, and take necessary preventive measures like keeping the Linux kernel up-to-date and monitoring system activities. Kernel developers are also expected to release a patch to fix the vulnerability soon. To stay updated with the latest information, refer to the original references provided above.

Timeline

Published on: 01/18/2024 16:15:08 UTC
Last modified on: 01/26/2024 19:00:06 UTC