AuroraMiddleware/libtomcrypt
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fix possible missing free of rnd and rndi

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There could have been a 'goto error', which misses the free of rnd and
rndi even if they were initialized.
This could happen in cases where a private key operation was done and
afterwards one of the operations like reading back or conversion, would
have failed (which is likely not to happen)

This also includes a proposed improvement from the OLPC project to free
elements in the reverse order as they were allocated.
This commit is contained in:
Steffen Jaeckel 2014-06-15 11:51:38 +02:00
parent 48f521688f
commit 30278d1121
1 changed files with 22 additions and 20 deletions
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42
src/pk/rsa/rsa_exptmod.c
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@ -35,7 +35,7 @@ int rsa_exptmod(const unsigned char *in, unsigned long inlen,
{
void *tmp, *tmpa, *tmpb;
#ifdef LTC_RSA_BLINDING
void *rnd = NULL, *rndi = NULL /* inverse of rnd */;
void *rnd, *rndi /* inverse of rnd */;
#endif
unsigned long x;
int err;
@ -56,7 +56,11 @@ int rsa_exptmod(const unsigned char *in, unsigned long inlen,
}
/* init and copy into tmp */
if ((err = mp_init_multi(&tmp, &tmpa, &tmpb, NULL)) != CRYPT_OK)
if ((err = mp_init_multi(&tmp, &tmpa, &tmpb,
#ifdef LTC_RSA_BLINDING
&rnd, &rndi,
#endif /* LTC_RSA_BLINDING */
NULL)) != CRYPT_OK)
{ return err; }
if ((err = mp_read_unsigned_bin(tmp, (unsigned char *)in, (int)inlen)) != CRYPT_OK)
{ goto error; }
@ -71,52 +75,50 @@ int rsa_exptmod(const unsigned char *in, unsigned long inlen,
/* are we using the private exponent and is the key optimized? */
if (which == PK_PRIVATE) {
#ifdef LTC_RSA_BLINDING
if ((err = mp_init_multi(&rnd, &rndi, NULL)) != CRYPT_OK)
{ goto error; }
/* do blinding */
err = mp_rand(rnd, mp_count_bits(key->N));
if (err != CRYPT_OK) {
goto error_blind;
goto error;
}
/* rndi = 1/rnd mod N */
err = mp_invmod(rnd, key->N, rndi);
if (err != CRYPT_OK) {
goto error_blind;
goto error;
}
/* rnd = rnd^e */
err = mp_exptmod( rnd, key->e, key->N, rnd);
if (err != CRYPT_OK) {
goto error_blind;
goto error;
}
/* tmp = tmp*rnd mod N */
err = mp_mulmod( tmp, rnd, key->N, tmp);
if (err != CRYPT_OK) {
goto error_blind;
goto error;
}
#endif /* LTC_RSA_BLINDING */
/* tmpa = tmp^dP mod p */
if ((err = mp_exptmod(tmp, key->dP, key->p, tmpa)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_exptmod(tmp, key->dP, key->p, tmpa)) != CRYPT_OK) { goto error; }
/* tmpb = tmp^dQ mod q */
if ((err = mp_exptmod(tmp, key->dQ, key->q, tmpb)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_exptmod(tmp, key->dQ, key->q, tmpb)) != CRYPT_OK) { goto error; }
/* tmp = (tmpa - tmpb) * qInv (mod p) */
if ((err = mp_sub(tmpa, tmpb, tmp)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_mulmod(tmp, key->qP, key->p, tmp)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_sub(tmpa, tmpb, tmp)) != CRYPT_OK) { goto error; }
if ((err = mp_mulmod(tmp, key->qP, key->p, tmp)) != CRYPT_OK) { goto error; }
/* tmp = tmpb + q * tmp */
if ((err = mp_mul(tmp, key->q, tmp)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_add(tmp, tmpb, tmp)) != CRYPT_OK) { goto error_blind; }
if ((err = mp_mul(tmp, key->q, tmp)) != CRYPT_OK) { goto error; }
if ((err = mp_add(tmp, tmpb, tmp)) != CRYPT_OK) { goto error; }
#ifdef LTC_RSA_BLINDING
/* unblind */
err = mp_mulmod( tmp, rndi, key->N, tmp);
if (err != CRYPT_OK) {
goto error_blind;
goto error;
}
#endif
} else {
@ -145,12 +147,12 @@ int rsa_exptmod(const unsigned char *in, unsigned long inlen,
/* clean up and return */
err = CRYPT_OK;
error_blind:
#ifdef LTC_RSA_BLINDING
mp_clear_multi(rnd, rndi, NULL);
#endif
error:
mp_clear_multi(tmp, tmpa, tmpb, NULL);
mp_clear_multi(
#ifdef LTC_RSA_BLINDING
rndi, rnd,
#endif /* LTC_RSA_BLINDING */
tmpb, tmpa, tmp, NULL);
return err;
}