2019-05-28 14:35:38

by Elena Petrova

Subject: [PATCH] arm64 sha2-ce finup: correct digest for empty data

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: [email protected]
Signed-off-by: Elena Petrova <[email protected]>
---
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

2019-05-28 14:37:22

by Ard Biesheuvel

Subject: Re: [PATCH] arm64 sha2-ce finup: correct digest for empty data

On Tue, 28 May 2019 at 16:35, Elena Petrova <[email protected]> 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: [email protected]
> Signed-off-by: Elena Petrova <[email protected]>

Thanks again

Reviewed-by: Ard Biesheuvel <[email protected]>

> ---
> 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
>

2019-06-06 06:52:58

by Herbert Xu

Subject: Re: [PATCH] crypto: arm64/sha2-ce - correct digest for empty data in finup

On Tue, May 28, 2019 at 03:35:06PM +0100, Elena Petrova 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: [email protected]
> Signed-off-by: Elena Petrova <[email protected]>
> Reviewed-by: Ard Biesheuvel <[email protected]>
> ---
> arch/arm64/crypto/sha2-ce-glue.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Patch applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt