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psa: cipher: Fix invalid output buffer usage in psa_cipher_encrypt()

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Don't use the output buffer in psa_cipher_encrypt()
to pass the generated IV to the driver as local
attacker could potentially control it.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
This commit is contained in:
Ronald Cron 2021-07-09 18:44:58 +02:00
parent 13ed5c1c05
commit c6e6f50d47
1 changed files with 20 additions and 11 deletions
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31
library/psa_crypto.c
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@ -3502,8 +3502,8 @@ psa_status_t psa_cipher_encrypt( mbedtls_svc_key_id_t key,
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_slot_t *slot = NULL;
psa_key_type_t key_type;
size_t iv_length;
uint8_t local_iv[PSA_CIPHER_IV_MAX_SIZE];
size_t default_iv_length = 0;
if( ! PSA_ALG_IS_CIPHER( alg ) )
{
@ -3521,26 +3521,31 @@ psa_status_t psa_cipher_encrypt( mbedtls_svc_key_id_t key,
.core = slot->attr
};
key_type = slot->attr.type;
iv_length = PSA_CIPHER_IV_LENGTH( key_type, alg );
if( iv_length > 0 )
default_iv_length = PSA_CIPHER_IV_LENGTH( slot->attr.type, alg );
if( default_iv_length > PSA_CIPHER_IV_MAX_SIZE )
{
if( output_size < iv_length )
status = PSA_ERROR_GENERIC_ERROR;
goto exit;
}
if( default_iv_length > 0 )
{
if( output_size < default_iv_length )
{
status = PSA_ERROR_BUFFER_TOO_SMALL;
goto exit;
}
status = psa_generate_random( output, iv_length );
status = psa_generate_random( local_iv, default_iv_length );
if( status != PSA_SUCCESS )
goto exit;
}
status = psa_driver_wrapper_cipher_encrypt(
&attributes, slot->key.data, slot->key.bytes,
alg, output, iv_length, input, input_length,
output + iv_length, output_size - iv_length, output_length );
alg, local_iv, default_iv_length, input, input_length,
output + default_iv_length, output_size - default_iv_length,
output_length );
exit:
unlock_status = psa_unlock_key_slot( slot );
@ -3548,7 +3553,11 @@ exit:
status = unlock_status;
if( status == PSA_SUCCESS )
*output_length += iv_length;
{
if( default_iv_length > 0 )
memcpy( output, local_iv, default_iv_length );
*output_length += default_iv_length;
}
else
*output_length = 0;