Re: [PATCH v5 2/2] kasan: Add strscpy() test to trigger tag fault on arm64

[Catalin Marinas]

On Wed, Apr 02, 2025 at 05:07:00PM -0700, Peter Collingbourne wrote:
> From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> 
> When we invoke strscpy() with a maximum size of N bytes, it assumes
> that:
> - It can always read N bytes from the source.
> - It always write N bytes (zero-padded) to the destination.
> 
> On aarch64 with Memory Tagging Extension enabled if we pass an N that is
> bigger then the source buffer, it would previously trigger an MTE fault.
> 
> Implement a KASAN KUnit test that triggers the issue with the previous
> implementation of read_word_at_a_time() on aarch64 with MTE enabled.
> 
> Cc: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Co-developed-by: Peter Collingbourne <pcc@xxxxxxxxxx>
> Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx>
> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Link: https://linux-review.googlesource.com/id/If88e396b9e7c058c1a4b5a252274120e77b1898a

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>