From 101e99c23af9460890edc9055141e6aba6d3e08a Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 3 Jul 2024 12:04:31 -0700 Subject: [PATCH] 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: Sami Tolvanen Acked-by: Ard Biesheuvel Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- crypto/testmgr.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/crypto/testmgr.c b/crypto/testmgr.c index a780b615f8c6..f02cb075bd68 100644 --- a/crypto/testmgr.c +++ b/crypto/testmgr.c @@ -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;