From 07bed46f332fce8c1d157689a2cdf915a982ae34 Mon Sep 17 00:00:00 2001 From: "Dr. Stephen Henson" Date: Fri, 5 Aug 2016 14:26:03 +0100 Subject: [PATCH] Check for errors in BN_bn2dec() 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 --- crypto/bn/bn_print.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/crypto/bn/bn_print.c b/crypto/bn/bn_print.c index 8672c7e3b3..f6030ff14c 100644 --- a/crypto/bn/bn_print.c +++ b/crypto/bn/bn_print.c @@ -62,6 +62,7 @@ char *BN_bn2dec(const BIGNUM *a) char *p; BIGNUM *t = NULL; BN_ULONG *bn_data = NULL, *lp; + int bn_data_num; /*- * get an upper bound for the length of the decimal integer @@ -71,7 +72,8 @@ char *BN_bn2dec(const BIGNUM *a) */ i = BN_num_bits(a) * 3; num = (i / 10 + i / 1000 + 1) + 1; - bn_data = OPENSSL_malloc((num / BN_DEC_NUM + 1) * sizeof(BN_ULONG)); + 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); @@ -93,7 +95,11 @@ char *BN_bn2dec(const BIGNUM *a) i = 0; while (!BN_is_zero(t)) { *lp = BN_div_word(t, BN_DEC_CONV); + if (*lp == (BN_ULONG)-1) + goto err; lp++; + if (lp - bn_data >= bn_data_num) + goto err; } lp--; /* -- 2.25.1