From 6bd934de1e393466b319d29c4427598fda096c57 Mon Sep 17 00:00:00 2001
From: Elena Petrova <lenaptr@google.com>
Date: Tue, 28 May 2019 15:35:06 +0100
Subject: [PATCH] crypto: arm64/sha2-ce - correct digest for empty data in finup
Git-commit: 6bd934de1e393466b319d29c4427598fda096c57
Patch-mainline: v5.3-rc1
References: bsc#1051510

The sha256-ce finup implementation for ARM64 produces wrong digest
for empty input (len=0). Expected: the actual digest, result: initial
value of SHA internal state. The error is in sha256_ce_finup:
for empty data `finalize` will be 1, so the code is relying on
sha2_ce_transform to make the final round. However, in
sha256_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: 03802f6a80b3a ("crypto: arm64/sha2-ce - move SHA-224/256 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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 arch/arm64/crypto/sha2-ce-glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/crypto/sha2-ce-glue.c
+++ b/arch/arm64/crypto/sha2-ce-glue.c
@@ -50,7 +50,7 @@ static int sha256_ce_finup(struct shash_
 			   unsigned int len, u8 *out)
 {
 	struct sha256_ce_state *sctx = shash_desc_ctx(desc);
-	bool finalize = !sctx->sst.count && !(len % SHA256_BLOCK_SIZE);
+	bool finalize = !sctx->sst.count && !(len % SHA256_BLOCK_SIZE) && len;
 
 	if (!may_use_simd()) {
 		if (len)