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 23:36:55 +0100 |
commit | 6555a8941bd6be5790d3b45c41de23234a8e527f (patch) | |
tree | af55eff2e0d2f9bafdd91fbfe249b288485fe739 /crypto/rsa/rsa_ssl.c | |
parent | d5e37fc871be6910db931790b70323c78b332dff (diff) |
Fix memory overrun in rsa padding check functions
Backported from d7f5e5ae6d5
Fixes #8364 and #8357
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/8438)
Diffstat (limited to 'crypto/rsa/rsa_ssl.c')
-rw-r--r-- | crypto/rsa/rsa_ssl.c | 33 |
1 files changed, 18 insertions, 15 deletions
diff --git a/crypto/rsa/rsa_ssl.c b/crypto/rsa/rsa_ssl.c index e9a5fe2385..61751fe6f1 100644 --- a/crypto/rsa/rsa_ssl.c +++ b/crypto/rsa/rsa_ssl.c @@ -104,7 +104,7 @@ int RSA_padding_add_SSLv23(unsigned char *to, int tlen, /* * Copy of RSA_padding_check_PKCS1_type_2 with a twist that rejects padding - * if nul delimiter is preceded by 8 consecutive 0x03 bytes. It also + * if nul delimiter is not preceded by 8 consecutive 0x03 bytes. It also * preserves error code reporting for backward compatibility. */ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, @@ -116,7 +116,10 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, unsigned int good, found_zero_byte, mask, threes_in_row; int zero_index = 0, msg_index, mlen = -1, err; - if (flen < 10) { + if (tlen <= 0 || flen <= 0) + return -1; + + if (flen > num || num < 11) { RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL); return (-1); } @@ -138,10 +141,9 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, from -= 1 & mask; *--em = *from & mask; } - from = em; - good = constant_time_is_zero(from[0]); - good &= constant_time_eq(from[1], 2); + good = constant_time_is_zero(em[0]); + good &= constant_time_eq(em[1], 2); err = constant_time_select_int(good, 0, RSA_R_BLOCK_TYPE_IS_NOT_02); mask = ~good; @@ -149,18 +151,18 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, found_zero_byte = 0; threes_in_row = 0; for (i = 2; i < num; i++) { - unsigned int equals0 = constant_time_is_zero(from[i]); + unsigned int equals0 = constant_time_is_zero(em[i]); zero_index = constant_time_select_int(~found_zero_byte & equals0, i, zero_index); found_zero_byte |= equals0; threes_in_row += 1 & ~found_zero_byte; - threes_in_row &= found_zero_byte | constant_time_eq(from[i], 3); + threes_in_row &= found_zero_byte | constant_time_eq(em[i], 3); } /* - * PS must be at least 8 bytes long, and it starts two bytes into |from|. + * PS must be at least 8 bytes long, and it starts two bytes into |em|. * If we never found a 0-byte, then |zero_index| is 0 and the check * also fails. */ @@ -169,7 +171,7 @@ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, RSA_R_NULL_BEFORE_BLOCK_MISSING); mask = ~good; - good &= constant_time_lt(threes_in_row, 8); + good &= constant_time_ge(threes_in_row, 8); err = constant_time_select_int(mask | good, err, RSA_R_SSLV3_ROLLBACK_ATTACK); mask = ~good; @@ -197,15 +199,16 @@ int RSA_padding_check_SSLv23(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(num, tlen), num, tlen); + tlen = constant_time_select_int(constant_time_lt(num - 11, tlen), + num - 11, tlen); msg_index = constant_time_select_int(good, msg_index, num - tlen); mlen = num - msg_index; - for (from += 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, num); - from -= tlen & equals; /* if (i == mlen) rewind */ - mask &= mask ^ equals; /* if (i == mlen) 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, em[msg_index++], to[i]); } OPENSSL_cleanse(em, num); |