Re: Typecasting a void pointer to unsigned long in zsmalloc.c

Costa Shulyupin <[email protected]> Thu, 23 Jan 2025 23:09:47 +0200
Newsgroups org.kernelnewbies.kernelnewbies
Message-ID <CADDUTFzN=BpNEOQB0r=rRRtiXNkgHzZpBsPfEgaLwJebBoPR1w@mail.gmail.com>
Hi. I've found this:

Pointers are __u64, cast from/to a uintptr_t on the userspace side and
from/to a void __user * in the kernel. Try really hard not to delay this
conversion or worse, fiddle the raw __u64 through your code since that
diminishes the checking tools like sparse can provide. The macro
u64_to_user_ptr can be used in the kernel to avoid warnings about integers
and pointers of different sizes.

https://origin.kernel.org/doc/html/latest/process/botching-up-ioctls.html#:~:text=Pointers%20are%20__u64

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