Commit 101e99c2 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: testmgr - generate power-of-2 lengths more often 



Implementations of hash functions often have special cases when lengths
are a multiple of the hash function's internal block size (e.g. 64 for
SHA-256, 128 for SHA-512).  Currently, when the fuzz testing code
generates lengths, it doesn't prefer any length mod 64 over any other.
This limits the coverage of these special cases.

Therefore, this patch updates the fuzz testing code to generate
power-of-2 lengths and divide messages exactly in half a bit more often.

Reviewed-by: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent dd52b5ee

crypto/testmgr.c

+12 −4
Original line number Diff line number Diff line
@@ -916,14 +916,20 @@ static unsigned int generate_random_length(struct rnd_state *rng, 


	switch (prandom_u32_below(rng, 4)) {

	case 0:

		return len % 64;

		len %= 64;

		break;

	case 1:

		return len % 256;

		len %= 256;

		break;

	case 2:

		return len % 1024;

		len %= 1024;

		break;

	default:

		return len;

		break;

	}

	if (len && prandom_u32_below(rng, 4) == 0)

		len = rounddown_pow_of_two(len);

	return len;

}



/* Flip a random bit in the given nonempty data buffer */
@@ -1019,6 +1025,8 @@ static char *generate_random_sgl_divisions(struct rnd_state *rng, 


		if (div == &divs[max_divs - 1] || prandom_bool(rng))

			this_len = remaining;

		else if (prandom_u32_below(rng, 4) == 0)

			this_len = (remaining + 1) / 2;

		else

			this_len = prandom_u32_inclusive(rng, 1, remaining);

		div->proportion_of_total = this_len;