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
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
-
Nitrux 6.0 Now Ready to Rock Your World
The latest iteration of the Debian-based distribution includes all kinds of newness.
-
Linux Foundation Reports that Open Source Delivers Better ROI
In a report that may surprise no one in the Linux community, the Linux Foundation found that businesses are finding a 5X return on investment with open source software.
-
Keep Android Open
Google has announced that, soon, anyone looking to develop Android apps will have to first register centrally with Google.
-
Kernel 7.0 Now in Testing
Linus Torvalds has announced the first Release Candidate (RC) for the 7.x kernel is available for those who want to test it.
-
Introducing matrixOS, an Immutable Gentoo-Based Linux Distro
It was only a matter of time before a developer decided one of the most challenging Linux distributions needed to be immutable.
-
Chaos Comes to KDE in KaOS
KaOS devs are making a major change to the distribution, and it all comes down to one system.
-
New Linux Botnet Discovered
The SSHStalker botnet uses IRC C2 to control systems via legacy Linux kernel exploits.
-
The Next Linux Kernel Turns 7.0
Linus Torvalds has announced that after Linux kernel 6.19, we'll finally reach the 7.0 iteration stage.
-
Linux From Scratch Drops SysVinit Support
LFS will no longer support SysVinit.
-
LibreOffice 26.2 Now Available
With new features, improvements, and bug fixes, LibreOffice 26.2 delivers a modern, polished office suite without compromise.