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MAC setup: support 0-length HMAC key

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Avoid undefined behavior when using a 0-length HMAC key (Asan
complained).
This commit is contained in:
Gilles Peskine 2018-07-12 17:07:03 +02:00 committed by itayzafrir
parent 01126fae7f
commit 9688997301
1 changed files with 5 additions and 1 deletions
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6
library/psa_crypto.c
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@ -1435,7 +1435,11 @@ static psa_status_t psa_hmac_setup_internal( psa_hmac_internal_data *hmac,
if( status != PSA_SUCCESS )
return( status );
}
else
/* A 0-length key is not commonly used in HMAC when used as a MAC,
* but it is permitted. It is common when HMAC is used in HKDF, for
* example. Don't call `memcpy` in the 0-length because `key` could be
* an invalid pointer which would make the behavior undefined. */
else if( key_length != 0 )
memcpy( ipad, key, key_length );
/* ipad contains the key followed by garbage. Xor and fill with 0x36