Zack's Kernel News
Zack's Kernel News
In kernel news: Heap Hardening Against Hostile Spraying; and Core Contention Improvements … or Not.
Heap Hardening Against Hostile Spraying
Ruiqi Gong wanted to address the generic security threat of "heap spraying" in the Linux kernel. Heap spraying is when an attacker knows the memory address of a critical part of the system and makes a large number of malloc() calls trying to allocate memory at that specific address. In the event of certain types of kernel bugs, one of those malloc() calls might succeed, giving the attacker the ability to overwrite the critical part of the system with their own malicious code. Heap spraying is not a security vulnerability in itself, because user software could legitimately want to issue many malloc() calls. Rather, heap spraying is a way to exploit other bugs that may exist in the kernel.
Because heap spraying itself is not a bug or vulnerability, it poses a fascinating problem in terms of how best to reduce the ability of attackers to make use of it. For example, Ruiqi pointed out that slab caches can be shared among different subsystems and modules. A slab cache is a region of memory allocated all at once on the grounds that the calling routine knows it will need that much memory eventually.
Slab caches are more efficient than doing a bunch of piecemeal allocations as-needed, but they also present a visible target for heap spraying attacks. At the same time, as Ruiqi said, it wouldn't be realistic to disable slab caching in the kernel, because that feature is in wide use by user software, all of which would need to be rewritten and would suffer a significant performance penalty.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe 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
-
The GNU Project Celebrates Its 40th Birthday
September 27 marks the 40th anniversary of the GNU Project, and it was celebrated with a hacker meeting in Biel/Bienne, Switzerland.
-
Linux Kernel Reducing Long-Term Support
LTS support for the Linux kernel is about to undergo some serious changes that will have a considerable impact on the future.
-
Fedora 39 Beta Now Available for Testing
For fans and users of Fedora Linux, the first beta of release 39 is now available, which is a minor upgrade but does include GNOME 45.
-
Fedora Linux 40 to Drop X11 for KDE Plasma
When Fedora 40 arrives in 2024, there will be a few big changes coming, especially for the KDE Plasma option.
-
Real-Time Ubuntu Available in AWS Marketplace
Anyone looking for a Linux distribution for real-time processing could do a whole lot worse than Real-Time Ubuntu.
-
KSMBD Finally Reaches a Stable State
For those who've been looking forward to the first release of KSMBD, after two years it's no longer considered experimental.
-
Nitrux 3.0.0 Has Been Released
The latest version of Nitrux brings plenty of innovation and fresh apps to the table.
-
Linux From Scratch 12.0 Now Available
If you're looking to roll your own Linux distribution, the latest version of Linux From Scratch is now available with plenty of updates.
-
Linux Kernel 6.5 Has Been Released
The newest Linux kernel, version 6.5, now includes initial support for two very exciting features.
-
UbuntuDDE 23.04 Now Available
A new version of the UbuntuDDE remix has finally arrived with all the updates from the Deepin desktop and everything that comes with the Ubuntu 23.04 base.