CVE-2021-46943: Resolving Linux Kernel Vulnerability in Media Staging with Proper Set

Recently, the Linux kernel has patched a major vulnerability that existed within the media staging (intel-ipu3) module. The vulnerability, identified by the CVE number CVE-2021-46943, could lead to system crashes, resource exhaustion, and overall instabilities due to the mishandling of set_fmt errors. This article seeks to provide a comprehensive breakdown of the issue, its impact, and the solution provided by the Linux kernel team. We will cover the code snippets relevant to this issue, their potential implications, and the original references necessary for understanding the details.

Problem

In the media staging module (staging/intel-ipu3), there was an issue with the error handling during the set_fmt operation. If there was an error encountered during set_fmt execution, the previous sizes would be overwritten with an invalid configuration, causing severe issues within the Linux kernel. One such example issue was the allocation of an impractical 4 GiB of RAM by the v4l2-compliance module, eventually leading to the following Out of Memory (OOPs) error within the system:

[ 38.662975] ipu3-imgu 000:00:05.: swiotlb buffer is full (sz: 4096 bytes)
[ 38.662980] DMA: Out of SW-IOMMU space for 4096 bytes at device 000:00:05.
[ 38.663010] general protection fault: 000 [#1] PREEMPT SMP

Exploit Details

An attacker able to trigger an error during the set_fmt operation in the staging/intel-ipu3 module of an affected Linux kernel could exploit this vulnerability to potentially cause a denial of service (DoS) in the system by consuming extensive system resources, such as RAM, and causing kernel-level crashes.

Patch

The Linux kernel team has remedied this vulnerability by implementing better error handling for set_fmt operation in the staging/intel-ipu3 module. The improved error handling now prevents the overwriting of previous sizes with invalid configurations, ensuring that resource allocations are not disproportionately large and that kernel crashes are avoided.

To view the complete patch for this vulnerability, you can refer to the Linux kernel Git commit.

Conclusion

CVE-2021-46943 was a significant vulnerability in the Linux kernel that could allow attackers to cause extensive resource allocations and kernel crashes. Fortunately, this vulnerability has now been patched with improved error handling during set_fmt operations in the staging/intel-ipu3 module, mitigating the potential risks associated with this issue. It is always crucial to apply security patches in a timely manner to protect your systems from potential exploits. Be sure to update your Linux kernel to prevent exploitation of this vulnerability and stay vigilant for other potential security risks.

Timeline

Published on: 02/27/2024 19:04:06 UTC
Last modified on: 04/10/2024 19:54:14 UTC