crypto: arm64/sha1-ce - correct digest for empty data in finup

The sha1-ce finup implementation for ARM64 produces wrong digest
for empty input (len=0). Expected: da39a3ee..., result: 67452301...
(initial value of SHA internal state). The error is in sha1_ce_finup:
for empty data `finalize` will be 1, so the code is relying on
sha1_ce_transform to make the final round. However, in
sha1_base_do_update, the block function will not be called when
len == 0.

Fix it by setting finalize to 0 if data is empty.

Fixes: 07eb54d3 ("crypto: arm64/sha1-ce - move SHA-1 ARMv8 implementation to base layer")
Cc: stable@vger.kernel.org
Signed-off-by: Elena Petrova <lenaptr@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/sha1-ce-glue.c

@@ -55,7 +55,7 @@ static int sha1_ce_finup(struct shash_desc *desc, const u8 *data,
 			 unsigned int len, u8 *out)
 {
 	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
-	bool finalize = !sctx->sst.count && !(len % SHA1_BLOCK_SIZE);
+	bool finalize = !sctx->sst.count && !(len % SHA1_BLOCK_SIZE) && len;
 
 	if (!crypto_simd_usable())
 		return crypto_sha1_finup(desc, data, len, out);