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authorBernd Edlinger <bernd.edlinger@hotmail.de>2019-02-28 10:08:18 +0100
committerBernd Edlinger <bernd.edlinger@hotmail.de>2019-03-07 23:04:39 +0100
commit7ebbb293e1d68c014e50dc49944aba0b72f35074 (patch)
treef153852ba109006ee45235dc49f49a95bfe61e0a /crypto/rsa/rsa_oaep.c
parenta8e129a0923b17751655f2e98d5d4c2ae144e3fe (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.c26
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]);
}
/*