Let BN_rand_range() abort with an error after 100 iterations

without success.

diff --git a/CHANGES b/CHANGES
index 26c84b059622e47e227d2830a8529a86251afcfb..3067dc6389005beae8755d3eec486dc22f9b6544 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,10 @@
 
  Changes between 0.9.7 and 0.9.8  [xx XXX 2002]
 
+  *) Let BN_rand_range() abort with an error after 100 iterations
+     without success (which indicates a broken PRNG).
+     [Bodo Moeller]
+
   *) Change BN_mod_sqrt() so that it verifies that the input value
      is really the square of the return value.  (Previously,
      BN_mod_sqrt would show GIGO behaviour.)

diff --git a/crypto/bn/bn_rand.c b/crypto/bn/bn_rand.c
index 9e08ccd22e78fca5cb4795cc35d3a6ab39429c19..e6705f7025bd82e039a7a261f45d1b76820fce15 100644 (file)
--- a/crypto/bn/bn_rand.c
+++ b/crypto/bn/bn_rand.c
@@ -230,6 +230,7 @@ static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
        {
        int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
        int n;
+       int count = 100;
 
        if (range->neg || BN_is_zero(range))
                {
@@ -263,6 +264,13 @@ static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
                                if (BN_cmp(r, range) >= 0)
                                        if (!BN_sub(r, r, range)) return 0;
                                }
+
+                       if (!--count)
+                               {
+                               BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
+                               return 0;
+                               }
+                       
                        }
                while (BN_cmp(r, range) >= 0);
                }
@@ -272,6 +280,12 @@ static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
                        {
                        /* range = 11..._2  or  range = 101..._2 */
                        if (!bn_rand(r, n, -1, 0)) return 0;
+
+                       if (!--count)
+                               {
+                               BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
+                               return 0;
+                               }
                        }
                while (BN_cmp(r, range) >= 0);
                }