Re: [PATCH v4 0/7] arm64: untag user pointers passed to the kernel

[Andrey Konovalov]

On Wed, Jun 27, 2018 at 5:05 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
> On Tue, Jun 26, 2018 at 7:29 PM, Catalin Marinas
> <catalin.marinas@xxxxxxx> wrote:
>> While I support this work, as a maintainer I'd like to understand
>> whether we'd be in a continuous chase of ABI breaks with every kernel
>> release or we have a better way to identify potential issues. Is there
>> any way to statically analyse conversions from __user ptr to long for
>> example? Or, could we get the compiler to do this for us?
>
>
> OK, got it, I'll try to figure out a way to find these conversions.

I've prototyped a checker on top of clang static analyzer (initially
looked at sparse, but couldn't find any documentation or examples).
The results are here [1], search for "warning: user pointer cast".
Sharing in case anybody wants to take a look, will look at them myself
tomorrow.

[1] https://gist.github.com/xairy/433edd5c86456a64026247cb2fef2115