Re: [PATCH v10 00/12] arm64: untag user pointers passed to the kernel

[Dave Hansen]

On 2/22/19 4:53 AM, Andrey Konovalov wrote:
> The following testing approaches has been taken to find potential issues
> with user pointer untagging:
> 
> 1. Static testing (with sparse [3] and separately with a custom static
>    analyzer based on Clang) to track casts of __user pointers to integer
>    types to find places where untagging needs to be done.

First of all, it's really cool that you took this approach.  Sounds like
there was a lot of systematic work to fix up the sites in the existing
codebase.

But, isn't this a _bit_ fragile going forward?  Folks can't just "make
sparse" to find issues with missing untags.  This seems like something
where we would ideally add an __tagged annotation (or something) to the
source tree and then have sparse rules that can look for missed untags.