If an oversize BIGNUM is presented to BN_bn2dec() it can cause
BN_div_word() to fail and not reduce the value of 't' resulting
in OOB writes to the bn_data buffer and eventually crashing.
Fix by checking return value of BN_div_word() and checking writes
don't overflow buffer.
Thanks to Shi Lei for reporting this bug.
CVE-2016-2182
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit
07bed46f332fce8c1d157689a2cdf915a982ae34)
Conflicts:
crypto/bn/bn_print.c
char *p;
BIGNUM *t = NULL;
BN_ULONG *bn_data = NULL, *lp;
char *p;
BIGNUM *t = NULL;
BN_ULONG *bn_data = NULL, *lp;
/*-
* get an upper bound for the length of the decimal integer
/*-
* get an upper bound for the length of the decimal integer
*/
i = BN_num_bits(a) * 3;
num = (i / 10 + i / 1000 + 1) + 1;
*/
i = BN_num_bits(a) * 3;
num = (i / 10 + i / 1000 + 1) + 1;
- bn_data =
- (BN_ULONG *)OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG));
- buf = (char *)OPENSSL_malloc(num + 3);
+ bn_data_num = num / BN_DEC_NUM + 1;
+ bn_data = OPENSSL_malloc(bn_data_num * sizeof(BN_ULONG));
+ buf = OPENSSL_malloc(num + 3);
if ((buf == NULL) || (bn_data == NULL)) {
BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
goto err;
if ((buf == NULL) || (bn_data == NULL)) {
BNerr(BN_F_BN_BN2DEC, ERR_R_MALLOC_FAILURE);
goto err;
i = 0;
while (!BN_is_zero(t)) {
*lp = BN_div_word(t, BN_DEC_CONV);
i = 0;
while (!BN_is_zero(t)) {
*lp = BN_div_word(t, BN_DEC_CONV);
+ if (*lp == (BN_ULONG)-1)
+ goto err;
+ if (lp - bn_data >= bn_data_num)
+ goto err;