On Tue, 28 May 2019 at 16:35, Elena Petrova lenaptr@google.com wrote:

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

Thanks again

Reviewed-by: Ard Biesheuvel ard.biesheuvel@linaro.org

---

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

diff --git a/arch/arm64/crypto/sha2-ce-glue.c b/arch/arm64/crypto/sha2-ce-glue.c index a725997e55f2..6a5ade974a35 100644 --- a/arch/arm64/crypto/sha2-ce-glue.c +++ b/arch/arm64/crypto/sha2-ce-glue.c @@ -60,7 +60,7 @@ static int sha256_ce_finup(struct shash_desc *desc, const u8 *data, 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 (!crypto_simd_usable()) {
            if (len)
  

-- 2.22.0.rc1.257.g3120a18244-goog