[PATCH 4.9 079/223] crypto: arm64/sha1-ce - correct digest for empty data in finup

From: Greg Kroah-Hartman
Date: Fri Aug 02 2019 - 05:43:33 EST

From: Elena Petrova <lenaptr@xxxxxxxxxx>

commit 1d4aaf16defa86d2665ae7db0259d6cb07e2091f upstream.

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: 07eb54d306f4 ("crypto: arm64/sha1-ce - move SHA-1 ARMv8 implementation to base layer")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Elena Petrova <lenaptr@xxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/arm64/crypto/sha1-ce-glue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/crypto/sha1-ce-glue.c
+++ b/arch/arm64/crypto/sha1-ce-glue.c
@@ -50,7 +50,7 @@ static int sha1_ce_finup(struct shash_de
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;

* Allow the asm code to perform the finalization if there is no