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powerpc/crypto: Use cheaper random numbers for crc-vpmsum self-test 

This code was filling a 64K buffer from /dev/urandom in order to
compute a CRC over (on average half of) it by two different methods,
comparing the CRCs, and repeating.

This is not a remotely security-critical application, so use the far
faster and cheaper prandom_u32() generator.

And, while we're at it, only fill as much of the buffer as we plan to use.

Signed-off-by: George Spelvin <lkml@sdf.org>
Acked-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
George Spelvin 2019-03-21 10:42:22 +00:00 committed by Michael Ellerman
parent 6917735e8f
commit 80d04b7fab
1 changed files with 3 additions and 7 deletions
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10
arch/powerpc/crypto/crc-vpmsum_test.c
View File

@ -78,16 +78,12 @@ static int __init crc_test_init(void)
pr_info("crc-vpmsum_test begins, %lu iterations\n", iterations);
for (i=0; i<iterations; i++) {
size_t len, offset;
size_t offset = prandom_u32_max(16);
size_t len = prandom_u32_max(MAX_CRC_LENGTH);
get_random_bytes(data, MAX_CRC_LENGTH);
get_random_bytes(&len, sizeof(len));
get_random_bytes(&offset, sizeof(offset));
len %= MAX_CRC_LENGTH;
offset &= 15;
if (len <= offset)
continue;
prandom_bytes(data, len);
len -= offset;
crypto_shash_update(crct10dif_shash, data+offset, len);