Don't leak db on error in RSA_padding_check_PKCS1_OAEP().

CID #183499.

input & ok jsing, ok mestre on first version

diff --git a/lib/libcrypto/rsa/rsa_oaep.c b/lib/libcrypto/rsa/rsa_oaep.c
index a629275..5552058 100644 (file)
--- a/lib/libcrypto/rsa/rsa_oaep.c
+++ b/lib/libcrypto/rsa/rsa_oaep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: rsa_oaep.c,v 1.27 2018/08/05 13:30:04 bcook Exp $ */
+/* $OpenBSD: rsa_oaep.c,v 1.28 2018/08/19 20:15:30 tb Exp $ */
 /* Written by Ulf Moeller. This software is distributed on an "AS IS"
    basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. */
 
@@ -126,8 +126,7 @@ RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
        }
 
        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 char *to, int tlen,
        maskeddb = padded_from + SHA_DIGEST_LENGTH;
 
        if (MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen))
-               return -1;
+               goto 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 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 err;
 
        if (timingsafe_memcmp(db, phash, SHA_DIGEST_LENGTH) != 0 || bad)
                goto decoding_err;
@@ -177,12 +176,13 @@ RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
        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
         */
        RSAerror(RSA_R_OAEP_DECODING_ERROR);
+ err:
        free(db);
        return -1;
 }