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

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.