Re: [PATCH 5/6] driver core: Add __alloc_size hint to devm allocators

[Kees Cook]

On Thu, Feb 02, 2023 at 10:56:29AM -0800, John Stultz wrote:
> That said, making sense of the error message isn't completely trivial
> either. I've been seeing a few cases recently of some of the new
> compiler tooling (I pinged you earlier on a CFI one) causing errors
> that developers aren't really sure how to address.  I know sometimes
> it's not easy to surface the errors with context to what was wrong,
> but at the risk of intense bike shedding, is there some way to provide
> something like "Likely array bounds error" instead of just "BRK
> handler: Fatal exception"?

Yeah, this is a result of the size trade-off that resulted in config
CONFIG_UBSAN_TRAP -- there ends up being no message about what went
wrong. I'd really like to have cleaner handling of this -- perhaps what
was done for KCFI could be applied to UBSAN as well, though this is an
area I don't know well myself. (i.e. encoding "this was a UBSAN trap"
in the trap itself.)

Sami or Ard, is this something that could be improved for arm64?

-- 
Kees Cook