CVE-2021-47030 | Patched Linux Kernel Vulnerability in mt76: mt7615 - Fixing Memory Leak in mt7615_coredump_work

Overview

In the Linux kernel, a vulnerability has been discovered and resolved relating to a memory leak in the mt7615_coredump_work(). This vulnerability may have been exploited by malicious actors to cause a Denial of Service attack or affect the overall stability of the system. In this long read, we will be discussing the vulnerability in detail, the associated code snippets, and links to the original references.

Vulnerability Details

The exposed vulnerability pertains to a possible memory leak in the mt7615_coredump_work() routine in the mt76: mt7615 driver. This issue bears similarities to another previously fixed vulnerability in mt7921_coredump_work(). If left unpatched, this vulnerability allows an attacker to exploit the mt76: mt7615 driver and cause memory leaks, which can eventually lead to system instability or facilitate Denial of Service (DoS) attacks.

Patch and Code Snippet

The patch applied fixes the memory leak vulnerability in mt7615_coredump_work(). The main change introduced is the addition of a kfree() call to ensure proper memory disposal. Here is the patched code snippet:

static void mt7615_coredump_work(struct work_struct *work)
{
    struct mt7615_dev *dev = container_of(work, struct mt7615_dev,
                                          coredump.work.work);
    ...
    mt76_connac_coredump_finish(&dev->mt76);
    kfree_skb(skb);

    /* call kfree() to release memory allocation */
    kfree(coredump.data);
}

Above, the added kfree(coredump.data); line ensures that the memory occupied by coredump.data is deallocated and the memory leak is resolved.

Original References and Exploit Details

The vulnerability, identified as CVE-2021-47030, was originally reported and tracked on the Linux Kernel official mailing list and further documented in the Linux Kernel Git repository. You can find more information about the vulnerability and the patch from these sources:

1. Linux Kernel Mailing List: Reported vulnerability - https://lore.kernel.org/all/20210929144928.5076-1-lorenzo@kernel.org/
2. Linux Kernel Git Repository: Vulnerability patch - https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b57e5123f378211e46dcc1d112ada6fed753959

To exploit this vulnerability, potential attackers would have to craft a specific input within the parameters of mt7615_coredump_work() to trigger the memory leak. Furthermore, a successful exploit would likely necessitate more sophisticated access and an in-depth understanding of the Linux kernel.

Conclusion

The vulnerability in the Linux kernel, CVE-2021-47030, regarding the memory leak in mt76: mt7615 has been addressed with a patch that ensures appropriate memory handling. Users are advised to update their systems with the latest Linux kernel version to remain secure against any potential exploitation of this vulnerability.

Timeline

Published on: 02/28/2024 09:15:39 UTC
Last modified on: 02/28/2024 14:06:45 UTC