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Fix two invalid memory reads in RSA OAEP mode.

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Submitted by: Ivan Nestlerode <inestlerode@us.ibm.com>
Reviewed by: steve
This commit is contained in:
Dr. Stephen Henson 2008-05-19 21:33:55 +00:00
parent 4bd4afa34e
commit 94fd382f8b
2 changed files with 23 additions and 8 deletions
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8
CHANGES
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@ -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 <inestlerode@us.ibm.com>]
*) Add TLS session ticket callback. This allows an application to set
TLS ticket cipher and HMAC keys rather than relying on hardcoded fixed

23
crypto/rsa/rsa_oaep.c
View File

@ -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);