[LTP] [PATCH] crypto: api - Fix generic algorithm self-test races

[Herbert Xu]

On Sat, Oct 05, 2024 at 08:06:18PM -0700, Eric Biggers wrote:
>
> I'm not sure about that, since the code that looks up algorithms only looks for
> algorithms that already have the CRYPTO_ALG_TESTED flag.

For normal lookups (one without CRYPTO_ALG_TESTED set in the mask
field), the core API will first look for a tested algorithm, and
if that fails then it will look for an untested algorithm.  The
second step should find the larval and then sleep on that until it's
done.
 
> That problem is caused by the use of fallback ciphers, though.

Sure that particular deadlock may have been due to a fallback,
but such dependencies exist outside of fallbacks too.  Especially
now that we have the fuzz testing which will dynamically load the
generic algorithms, it's easy to envisage a scenario where one
module registers an algorithm, which then triggers modprobe's on the
generic implementation of the same algorithm that then dead-locks.

PS it looks like there is an actual report of things breaking with
async testing in mv_cesa so I might revert/disable the async testing
after all.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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