diff --git a/CHANGES b/CHANGES index 2f26937ebddace2ef1beebd69ea1d4b1373ec9bd..b2b82024ad41a307b088f6b448dd26729d6df077 100644 --- a/CHANGES +++ b/CHANGES @@ -685,6 +685,14 @@ [NTT] Changes between 0.9.8g and 0.9.8h [xx XXX xxxx] + + *) RSA OAEP patches to fix two separate invalid memory reads. + The first one involves inputs when 'lzero' is greater than + 'SHA_DIGEST_LENGTH' (it would read about SHA_DIGEST_LENGTH bytes + before the beginning of from). The second one involves inputs where + the 'db' section contains nothing but zeroes (there is a one-byte + invalid read after the end of 'db'). + [Ivan Nesterlode ] *) Add TLS session ticket callback. This allows an application to set TLS ticket cipher and HMAC keys rather than relying on hardcoded fixed diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c index 45d6f6ef8a5eaa5435cc3e313cc7415ab1b405ff..3652677a99822b9cd47b9354bc0ba6366e3a2fc7 100644 --- a/crypto/rsa/rsa_oaep.c +++ b/crypto/rsa/rsa_oaep.c @@ -96,6 +96,7 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, const unsigned char *maskeddb; int lzero; unsigned char *db = NULL, seed[SHA_DIGEST_LENGTH], phash[SHA_DIGEST_LENGTH]; + unsigned char *padded_from; int bad = 0; if (--num < 2 * SHA_DIGEST_LENGTH + 1) @@ -106,8 +107,6 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, lzero = num - flen; if (lzero < 0) { - /* lzero == -1 */ - /* signalling this error immediately after detection might allow * for side-channel attacks (e.g. timing if 'plen' is huge * -- cf. James H. Manger, "A Chosen Ciphertext Attack on RSA Optimal @@ -115,20 +114,28 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, * so we use a 'bad' flag */ bad = 1; lzero = 0; + flen = num; /* don't overflow the memcpy to padded_from */ } - maskeddb = from - lzero + SHA_DIGEST_LENGTH; dblen = num - SHA_DIGEST_LENGTH; - db = OPENSSL_malloc(dblen); + db = OPENSSL_malloc(dblen + num); if (db == NULL) { RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, ERR_R_MALLOC_FAILURE); return -1; } + /* Always do this zero-padding copy (even when lzero == 0) + * to avoid leaking timing info about the value of lzero. */ + padded_from = db + dblen; + memset(padded_from, 0, lzero); + memcpy(padded_from + lzero, from, flen); + + maskeddb = padded_from + SHA_DIGEST_LENGTH; + MGF1(seed, SHA_DIGEST_LENGTH, maskeddb, dblen); - for (i = lzero; i < SHA_DIGEST_LENGTH; i++) - seed[i] ^= from[i - lzero]; + for (i = 0; i < SHA_DIGEST_LENGTH; i++) + seed[i] ^= padded_from[i]; MGF1(db, dblen, seed, SHA_DIGEST_LENGTH); for (i = 0; i < dblen; i++) @@ -143,13 +150,13 @@ int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen, for (i = SHA_DIGEST_LENGTH; i < dblen; i++) if (db[i] != 0x00) break; - if (db[i] != 0x01 || i++ >= dblen) + if (i == dblen || db[i] != 0x01) goto decoding_err; else { /* everything looks OK */ - mlen = dblen - i; + mlen = dblen - ++i; if (tlen < mlen) { RSAerr(RSA_F_RSA_PADDING_CHECK_PKCS1_OAEP, RSA_R_DATA_TOO_LARGE);