Root Exploit Vulnerability in Kernel 2.6.30
A recently discovered root exploit attacked the newest Linux versions and circumvented protection systems such as SELinux and AppArmor. A solution has been found.
An entry in the Internet Storm Center's Handler's Diary by Bojan Zdrnja entitled "A new fascinating Linux kernel vulnerability" describes the root exploit. The exploit code had been exposed by Brad Spengler, himself a developer for the grsecurity open source security application, in a "full-disclosure" on Grok.org. Zdrnja explains, "Why is it so fascinating? Because a source code audit of the vulnerable code would never find this vulnerability (well, actually, it is possible but I assure you that almost everyone would miss it). Spengler assures that only Kernel 2.6.30 and later are affected, with the exploit code running on 32-bit and 64-bit versions.
The security hole results from a vulnerability in the net/tun implementation. Even though the code correctly checks for a certain NULL variable, the compiler removes the if statement, thereby allowing access to otherwise inaccesible parts of memory. Zdrnja describes the "relatively easy" fix: "the check has to be done before assigning the value to the sk structure."
Thus the compiler introduces a vulnerability in the binary code that didn't exist in the source code, leading Zdrnja to the conclusion, "Fascinating research that again shows how security depends on every layer, and how even [a] very expensive source code audit can result in missed vulnerabilities."
ERRATA: Our original news indicated that Kernel 2.6.30 was previously released to customers primarily in a build for RHEL 5. We were wrong. The truth is that the exploit applies to Kernel 2.6.30 and later, as well as Kernel 2.6.18 in RHEL 5. The source code of the exploit, therefore, is compilable with different options. We apologize for our error.
Comments
comments powered by DisqusSubscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

News
-
OpenMandriva Lx 6.0 Available for Installation
The latest release of OpenMandriva has arrived with a new kernel, an updated Plasma desktop, and a server edition.
-
TrueNAS 25.04 Arrives with Thousands of Changes
One of the most popular Linux-based NAS solutions has rolled out the latest edition, based on Ubuntu 25.04.
-
Fedora 42 Available with Two New Spins
The latest release from the Fedora Project includes the usual updates, a new kernel, an official KDE Plasma spin, and a new System76 spin.
-
So Long, ArcoLinux
The ArcoLinux distribution is the latest Linux distribution to shut down.
-
What Open Source Pros Look for in a Job Role
Learn what professionals in technical and non-technical roles say is most important when seeking a new position.
-
Asahi Linux Runs into Issues with M4 Support
Due to Apple Silicon changes, the Asahi Linux project is at odds with adding support for the M4 chips.
-
Plasma 6.3.4 Now Available
Although not a major release, Plasma 6.3.4 does fix some bugs and offer a subtle change for the Plasma sidebar.
-
Linux Kernel 6.15 First Release Candidate Now Available
Linux Torvalds has announced that the release candidate for the final release of the Linux 6.15 series is now available.
-
Akamai Will Host kernel.org
The organization dedicated to cloud-based solutions has agreed to host kernel.org to deliver long-term stability for the development team.
-
Linux Kernel 6.14 Released
The latest Linux kernel has arrived with extra Rust support and more.
Confusion
RHEL 5?