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Fix buffer overflow with hashes larger than key size.

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Truncate input hashes to curve private key size as that is all that is required
for the internal implementation.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
This commit is contained in:
Paul Elliott 2023-02-09 14:30:24 +00:00
parent 01885fa5e5
commit 0290a76fc2
1 changed files with 18 additions and 4 deletions
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22
library/psa_crypto.c
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@ -3524,6 +3524,7 @@ psa_status_t mbedtls_psa_sign_hash_start(
const uint8_t *hash, size_t hash_length)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t required_hash_length;
if (!PSA_KEY_TYPE_IS_ECC(attributes->core.type)) {
return PSA_ERROR_NOT_SUPPORTED;
@ -3561,8 +3562,13 @@ psa_status_t mbedtls_psa_sign_hash_start(
operation->md_alg = mbedtls_hash_info_md_from_psa(hash_alg);
operation->alg = alg;
memcpy(operation->hash, hash, hash_length);
operation->hash_length = hash_length;
/* We only need to store the same length of hash as the private key size
* here, it would be truncated by the internal implementation anyway. */
required_hash_length = (hash_length < operation->coordinate_bytes ?
hash_length : operation->coordinate_bytes);
memcpy(operation->hash, hash, required_hash_length);
operation->hash_length = required_hash_length;
return PSA_SUCCESS;
@ -3574,6 +3580,7 @@ psa_status_t mbedtls_psa_sign_hash_start(
(void) hash;
(void) hash_length;
(void) status;
(void) required_hash_length;
return PSA_ERROR_NOT_SUPPORTED;
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) ||
@ -3722,6 +3729,7 @@ psa_status_t mbedtls_psa_verify_hash_start(
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t coordinate_bytes = 0;
size_t required_hash_length = 0;
if (!PSA_KEY_TYPE_IS_ECC(attributes->core.type)) {
return PSA_ERROR_NOT_SUPPORTED;
@ -3785,8 +3793,13 @@ psa_status_t mbedtls_psa_verify_hash_start(
mbedtls_ecdsa_restart_init(&operation->restart_ctx);
memcpy(operation->hash, hash, hash_length);
operation->hash_length = hash_length;
/* We only need to store the same length of hash as the private key size
* here, it would be truncated by the internal implementation anyway. */
required_hash_length = (hash_length < coordinate_bytes ? hash_length :
coordinate_bytes);
memcpy(operation->hash, hash, required_hash_length);
operation->hash_length = required_hash_length;
return PSA_SUCCESS;
#else
@ -3800,6 +3813,7 @@ psa_status_t mbedtls_psa_verify_hash_start(
(void) signature_length;
(void) status;
(void) coordinate_bytes;
(void) required_hash_length;
return PSA_ERROR_NOT_SUPPORTED;
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) ||