Source URL: https://binarygecko.com/race-conditions-in-linux-kernel-perf-events/
Source: Hacker News
Title: Race conditions in Linux Kernel perf events
Feedly Summary: Comments
AI Summary and Description: Yes
**Summary:**
The provided text details a vulnerability in the Linux kernel’s `perf_events` subsystem, specifically related to the management of auxiliary buffers within performance monitoring events. It reveals exploit strategies and proofs of concept (PoC) while emphasizing the risks posed by this vulnerability across various kernel versions. This vulnerability offers critical insights into kernel security, relevant to security professionals, as it showcases how certain features can be susceptible to exploitation.
**Detailed Description:**
The text outlines a significant vulnerability stemming from the `perf_events` subsystem within the Linux kernel, introduced around version 4.1. It highlights key aspects of this vulnerability, its exploitability, and the mechanics involved in utilizing it. The following points encapsulate the major points derived from the text:
– **Discovery and Disclosure:**
– The vulnerability was disclosed to the kernel security team via responsible disclosure.
– **Vulnerability Characteristics:**
– No CVE number is assigned until a fix is deployed; hence, awareness of the issue is crucial.
– The vulnerability persists even though it was introduced nearly 9 years ago.
– **Affected Components:**
– Primarily impacts the `perf_events` kernel subsystem and has implications for various distributions.
– Major Linux distributions like Debian and certain Android versions are reported as unaffected; however, the vulnerability is exploitable in “vanilla” kernel builds.
– **Underlying Mechanism:**
– The `perf_event` structure and associated auxiliary buffers are susceptible to a race condition. Exploiting this can allow attackers to manipulate kernel memory.
– The faulty locking mechanism can lead to a scenario where an auxiliary buffer is freed while still being accessed, allowing for potential memory corruption.
– **Exploit Strategy:**
– The exploit takes advantage of timing, racing against the process of freeing auxiliary buffer memory.
– Users can orchestrate memory mappings that should not be accessible or writable, leading to unauthorized access and manipulation of kernel memory.
– **Operating Environment:**
– While the described exploits were successfully demonstrated on fresh, default-configured kernels with no additional security features, such as page checks, they are typically mitigated in major distributions.
– **Practical Implications:**
– Security and compliance professionals should be acutely aware of this vulnerability as it poses a critical risk in environments utilizing affected kernel versions.
– Recommendations for practitioners include immediate evaluation of kernel versions in use, consideration of security patches, and investigation of any dependent systems or applications leveraging kernel performance features.
This detailed analysis underlines not only the technical intricacies of the identified vulnerability but also the broader implications for security practices and compliance measures within the sphere of kernel and information security. The potential legacy of this exploit spans across numerous operational contexts, emphasizing the need for diligent kernel version management and continuous security practices.