diff options
author | Bernd Edlinger <bernd.edlinger@hotmail.de> | 2019-02-28 10:08:18 +0100 |
---|---|---|
committer | Bernd Edlinger <bernd.edlinger@hotmail.de> | 2019-03-07 23:04:39 +0100 |
commit | 7ebbb293e1d68c014e50dc49944aba0b72f35074 (patch) | |
tree | f153852ba109006ee45235dc49f49a95bfe61e0a /crypto/rsa/rsa_oaep.c | |
parent | a8e129a0923b17751655f2e98d5d4c2ae144e3fe (diff) |
Fix memory overrun in rsa padding check functions
Fixes #8364 and #8357
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/8365)
(cherry picked from commit d7f5e5ae6d53f1387a42d210806cf5e9ed0882d6)
Diffstat (limited to 'crypto/rsa/rsa_oaep.c')
-rw-r--r-- | crypto/rsa/rsa_oaep.c | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/crypto/rsa/rsa_oaep.c b/crypto/rsa/rsa_oaep.c index 495821237f..8c2bab4524 100644 --- a/crypto/rsa/rsa_oaep.c +++ b/crypto/rsa/rsa_oaep.c @@ -1,5 +1,5 @@ /* - * Copyright 1999-2018 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1999-2019 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -149,7 +149,7 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, * |num| is the length of the modulus; |flen| is the length of the * encoded message. Therefore, for any |from| that was obtained by * decrypting a ciphertext, we must have |flen| <= |num|. Similarly, - * num < 2 * mdlen + 2 must hold for the modulus irrespective of + * |num| >= 2 * |mdlen| + 2 must hold for the modulus irrespective of * the ciphertext, see PKCS #1 v2.2, section 7.1.2. * This does not leak any side-channel information. */ @@ -185,17 +185,16 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, from -= 1 & mask; *--em = *from & mask; } - from = em; /* * The first byte must be zero, however we must not leak if this is * true. See James H. Manger, "A Chosen Ciphertext Attack on RSA * Optimal Asymmetric Encryption Padding (OAEP) [...]", CRYPTO 2001). */ - good = constant_time_is_zero(from[0]); + good = constant_time_is_zero(em[0]); - maskedseed = from + 1; - maskeddb = from + 1 + mdlen; + maskedseed = em + 1; + maskeddb = em + 1 + mdlen; if (PKCS1_MGF1(seed, mdlen, maskeddb, dblen, mgf1md)) goto cleanup; @@ -236,7 +235,7 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, mlen = dblen - msg_index; /* - * For good measure, do this check in constant tine as well. + * For good measure, do this check in constant time as well. */ good &= constant_time_ge(tlen, mlen); @@ -250,15 +249,16 @@ int RSA_padding_check_PKCS1_OAEP_mgf1(unsigned char *to, int tlen, * should be noted that failure is indistinguishable from normal * operation if |tlen| is fixed by protocol. */ - tlen = constant_time_select_int(constant_time_lt(dblen, tlen), dblen, tlen); + tlen = constant_time_select_int(constant_time_lt(dblen - mdlen - 1, tlen), + dblen - mdlen - 1, tlen); msg_index = constant_time_select_int(good, msg_index, dblen - tlen); mlen = dblen - msg_index; - for (from = db + msg_index, mask = good, i = 0; i < tlen; i++) { - unsigned int equals = constant_time_eq(i, mlen); + for (mask = good, i = 0; i < tlen; i++) { + unsigned int equals = constant_time_eq(msg_index, dblen); - from -= dblen & equals; /* if (i == dblen) rewind */ - mask &= mask ^ equals; /* if (i == dblen) mask = 0 */ - to[i] = constant_time_select_8(mask, from[i], to[i]); + msg_index -= tlen & equals; /* rewind at EOF */ + mask &= ~equals; /* mask = 0 at EOF */ + to[i] = constant_time_select_8(mask, db[msg_index++], to[i]); } /* |