generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix off-by-one in BN_rand

Browse Source 
If BN_rand is called with |bits| set to 1 and |top| set to 1 then a 1 byte
buffer overflow can occur. There are no such instances within the OpenSSL at
the moment.

Thanks to Mateusz Kocielski (LogicalTrust), Marek Kroemeke, Filip Palian for
discovering and reporting this issue.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
This commit is contained in:
Matt Caswell 2015-05-19 16:03:02 +01:00
parent 726b5e7132
commit b484b040e3
4 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
crypto/bn/bn.h
View File

@ -934,6 +934,7 @@ void ERR_load_BN_strings(void);
# define BN_R_ARG2_LT_ARG3 100
# define BN_R_BAD_RECIPROCAL 101
# define BN_R_BIGNUM_TOO_LONG 114
# define BN_R_BITS_TOO_SMALL 118
# define BN_R_CALLED_WITH_EVEN_MODULUS 102
# define BN_R_DIV_BY_ZERO 103
# define BN_R_ENCODING_ERROR 104

3
crypto/bn/bn_err.c
View File

@ -1,6 +1,6 @@
/* crypto/bn/bn_err.c */
/* ====================================================================
* Copyright (c) 1999-2007 The OpenSSL Project. All rights reserved.
* Copyright (c) 1999-2015 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -119,6 +119,7 @@ static ERR_STRING_DATA BN_str_reasons[] = {
{ERR_REASON(BN_R_ARG2_LT_ARG3), "arg2 lt arg3"},
{ERR_REASON(BN_R_BAD_RECIPROCAL), "bad reciprocal"},
{ERR_REASON(BN_R_BIGNUM_TOO_LONG), "bignum too long"},
{ERR_REASON(BN_R_BITS_TOO_SMALL), "bits too small"},
{ERR_REASON(BN_R_CALLED_WITH_EVEN_MODULUS), "called with even modulus"},
{ERR_REASON(BN_R_DIV_BY_ZERO), "div by zero"},
{ERR_REASON(BN_R_ENCODING_ERROR), "encoding error"},

7
crypto/bn/bn_rand.c
View File

@ -121,6 +121,11 @@ static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
int ret = 0, bit, bytes, mask;
time_t tim;
if (bits < 0 || (bits == 1 && top > 0)) {
BNerr(BN_F_BNRAND, BN_R_BITS_TOO_SMALL);
return 0;
}
if (bits == 0) {
BN_zero(rnd);
return 1;
@ -169,7 +174,7 @@ static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
}
#endif
if (top != -1) {
if (top >= 0) {
if (top) {
if (bit == 0) {
buf[0] = 1;

3
doc/crypto/BN_rand.pod
View File

@ -24,7 +24,8 @@ most significant bit of the random number can be zero. If B<top> is 0,
it is set to 1, and if B<top> is 1, the two most significant bits of
the number will be set to 1, so that the product of two such random
numbers will always have 2*B<bits> length. If B<bottom> is true, the
number will be odd.
number will be odd. The value of B<bits> must be zero or greater. If B<bits> is
1 then B<top> cannot also be 1.
BN_pseudo_rand() does the same, but pseudo-random numbers generated by
this function are not necessarily unpredictable. They can be used for