Zack's Kernel News
Zack's Kernel News
The month Zack Brown reports on wonky typecasting.
Wonky Typecasting
Tinkering with strange forces, Steven Rostedt felt that a particular struct in the kernel should be tucked away into a private file, and the parts of the kernel using that struct should only be given a pointer to it. However, some (but not all) compilers started to complain about those in-kernel users trying to dereference the pointer (i.e., to see what it pointed to, which Steven had rendered hidden and inaccessible).
However, it was a little more complicated than that. The code that dereferenced the pointer wasn't targeting this specific pointer; it would simply dereference any pointer that was handed to it. But in this case, the struct's pointer was a secret hidden struct and was thus different from the types of pointers that code was usually handed, so … boom.
To fix this, Steven went through a big pile of kernel code and changed a lot of pointer declarations so that the dereferencing code wouldn't complain anymore. He didn't change it to be more accurate; he just changed it so the dereferencing process itself wouldn't care what was at the end of its request.
[...]
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
-
Debian Unleashes Debian Libre Live
Debian Libre Live keeps your machine free of proprietary software.
-
Valve Announces Pending Release of Steam Machine
Shout it to the heavens: Steam Machine, powered by Linux, is set to arrive in 2026.
-
Happy Birthday, ADMIN Magazine!
ADMIN is celebrating its 15th anniversary with issue #90.
-
Another Linux Malware Discovered
Russian hackers use Hyper-V to hide malware within Linux virtual machines.
-
TUXEDO Computers Announces a New InfinityBook
TUXEDO Computers is at it again with a new InfinityBook that will meet your professional and gaming needs.
-
SUSE Dives into the Agentic AI Pool
SUSE becomes the first open source company to adopt agentic AI with SUSE Enterprise Linux 16.
-
Linux Now Runs Most Windows Games
The latest data shows that nearly 90 percent of Windows games can be played on Linux.
-
Fedora 43 Has Finally Landed
The Fedora Linux developers have announced their latest release, Fedora 43.
-
KDE Unleashes Plasma 6.5
The Plasma 6.5 desktop environment is now available with new features, improvements, and the usual bug fixes.
-
Xubuntu Site Possibly Hacked
It appears that the Xubuntu site was hacked and briefly served up a malicious ZIP file from its download page.