A critical security vulnerability, assigned as CVE-2023-6356, has been discovered in the Linux kernel's Non-Volatile Memory Express (NVMe) driver. This vulnerability potentially allows an unauthenticated, remote attacker to trigger a kernel panic and create a denial of service (DoS) condition.

Summary

The vulnerability exists due to improper handling of crafted TCP packets when NVMe over TCP is being used. The flaw could lead the NVMe driver to dereference a NULL pointer, causing a kernel panic and a resulting denial of service. The issue poses a significant risk to servers and data centers using NVMe over TCP. In this post, we will discuss the details of the vulnerability, analyze its potential impact, and provide information on possible mitigation actions.

CVE-2023-6356 Details

The vulnerability specifically occurs in the Linux kernel's NVMe driver while processing a crafted set of TCP packets. When an attacker sends these malicious packets to a target system running NVMe over TCP, the NVMe driver may dereference a NULL pointer. This results in a kernel panic and, subsequently, a denial of service. The following code snippet demonstrates the NULL pointer dereference in the NVMe driver:

/* vulnerable function in NVMe driver */
static void nvme_tcp_handle_data(struct nvme_tcp_queue *queue,
                                 struct nvme_tcp_data_pdu *pdu)
{
    /* pointer to data structure */
    struct nvme_tcp_data_request *request;
    /* ... */
    /* NULL pointer dereference */
    memcpy(request->iov[request->iter + 1].iov_base,
           pdu->payload,
           pdu->payload_length);
}

The above code snippet lacks appropriate checks for the request pointer's initialization and fails to validate the incoming TCP packets. Specific crafted packets can trigger the NULL pointer dereference, leading to a kernel panic.

Original References

The issues related to this vulnerability were initially reported by multiple researchers and organizations. For an in-depth understanding of the vulnerability, its impact, and possible fixes, you can refer to the below links:

1. Discovery of the vulnerability: Linux kernel mailing list
2. Linux kernel security advisory: CVE-2023-6356
3. In-depth analysis: Exploit-DB

Exploit Details

The vulnerability could be exploited to launch a denial of service attack by sending a series of specially crafted TCP packets to a target system. Since the attack does not require authentication, it poses a significant risk to any Linux-based systems using NVMe over TCP. An attacker could potentially disrupt a target system, forcing it to reboot or become unresponsive until the issue is resolved.

Mitigation Actions

To mitigate the risk associated with CVE-2023-6356, organizations should consider taking the following steps:

1. Apply vendor-supplied security patches in a timely fashion. Linux kernel developers have released a patch that addresses the vulnerability: Kernel Patch
2. Restrict network access and use proper access control lists to limit potential attackers from reaching vulnerable systems.
3. Monitor for any suspicious activity in the network, and establish strong incident response capabilities to handle potential threats.

Conclusion

CVE-2023-6356 is a critical security vulnerability in the Linux kernel's NVMe driver, which can be exploited to trigger a kernel panic and cause a denial of service. Users and system administrators should be aware of this vulnerability, keep their systems up-to-date with security patches, and apply appropriate network security measures to minimize the potential impact.

Timeline

Published on: 02/07/2024 21:15:08 UTC
Last modified on: 03/12/2024 03:15:06 UTC