On Sunday 19 August 2018 08:44:24 Theo Buehler wrote:
> Coverity complains about the case where EVP_Digest() fails, but there
> are a couple more.
One thing worth mentioning... previously it would return -1 without setting an
error, whereas now it will always set RSA_R_OAEP_DECODING_ERROR (even if the
underlying failure was something unrelated like a malloc failure). I'm not
overly concerned by this, but we could (if we wanted) keep the previous
behaviour by adding an 'err' label that jumps to the 'free(db);' line and use
that for non-decoding failures.
Either way, ok jsing@
> Index: rsa/rsa_oaep.c
> ===================================================================
> RCS file: /var/cvs/src/lib/libcrypto/rsa/rsa_oaep.c,v
> retrieving revision 1.27
> diff -u -p -r1.27 rsa_oaep.c
> --- rsa/rsa_oaep.c 5 Aug 2018 13:30:04 -0000 1.27
> +++ rsa/rsa_oaep.c 19 Aug 2018 06:38:52 -0000
> @@ -126,8 +126,7 @@ RSA_padding_check_PKCS1_OAEP(unsigned ch
> }
>
> dblen = num - SHA_DIGEST_LENGTH;
> - db = malloc(dblen + num);
> - if (db == NULL) {
> + if ((db = malloc(dblen + num)) == NULL) {
> RSAerror(ERR_R_MALLOC_FAILURE);
> return -1;
> }
> @@ -143,17 +142,17 @@ RSA_padding_check_PKCS1_OAEP(unsigned ch
> maskeddb = padded_from + SHA_DIGEST_LENGTH;
>
> if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen))
> - return -1;
> + goto decoding_err;
> for (i = 0; i < SHA_DIGEST_LENGTH; i++)
> seed[i] ^= padded_from[i];
>
> if (MGF1(db, dblen, seed, SHA_DIGEST_LENGTH))
> - return -1;
> + goto decoding_err;
> for (i = 0; i < dblen; i++)
> db[i] ^= maskeddb[i];
>
> if (!EVP_Digest((void *)param, plen, phash, NULL, EVP_sha1(), NULL))
> - return -1;
> + goto decoding_err;
>
> if (timingsafe_memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
> goto decoding_err;
> @@ -177,7 +176,7 @@ RSA_padding_check_PKCS1_OAEP(unsigned ch
> free(db);
> return mlen;
>
> -decoding_err:
> + decoding_err:
> /*
> * To avoid chosen ciphertext attacks, the error message should not
> * reveal which kind of decoding error happened
