Bug 335016: In mpp_pprime, do not choose 0 or 1 as 'x' (the random integer

in the Miller-Rabin probabilistic primality test).  r=nelson.

1 files changed, 5 insertions, 1 deletions

diff --git a/security/nss/lib/freebl/mpi/mpprime.c b/security/nss/lib/freebl/mpi/mpprime.c
index 4d6428118..ae8e49618 100644
--- a/security/nss/lib/freebl/mpi/mpprime.c
+++ b/security/nss/lib/freebl/mpi/mpprime.c
@@ -329,10 +329,14 @@ mp_err  mpp_pprime(mp_int *a, int nt)
   /* Do the test nt times... */
   for(iter = 0; iter < nt; iter++) {
 
-    /* Choose a random value for x < a          */
+    /* Choose a random value for 1 < x < a      */
     s_mp_pad(&x, USED(a));
     mpp_random(&x);
     MP_CHECKOK( mp_mod(&x, a, &x) );
+    if(mp_cmp_d(&x, 1) <= 0) {
+      iter--;    /* don't count this iteration */
+      continue;  /* choose a new x */
+    }
 
     /* Compute z = (x ** m) mod a               */
     MP_CHECKOK( mp_exptmod(&x, &m, a, &z) );