From 1c1baaa755f8a45ff61d3f281fb6c0b801f79469 Mon Sep 17 00:00:00 2001
From: Steffen Jaeckel <s@jaeckel.eu>
Date: Thu, 12 Nov 2015 01:18:00 +0100
Subject: [PATCH] Don't cast the potential problems away, handle them
 appropriately

---
 bn_mp_div.c         | 4 +++-
 bn_mp_dr_reduce.c   | 4 +++-
 bn_mp_exteuclid.c   | 6 +++---
 bn_mp_reduce_2k.c   | 4 +++-
 bn_mp_reduce_2k_l.c | 4 +++-
 bn_mp_toom_mul.c    | 4 +++-
 bn_mp_toom_sqr.c    | 4 +++-
 7 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/bn_mp_div.c b/bn_mp_div.c
index 3dc28c9..630f2dc 100644
--- a/bn_mp_div.c
+++ b/bn_mp_div.c
@@ -270,7 +270,9 @@ int mp_div (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
   }
 
   if (d != NULL) {
-    (void)mp_div_2d (&x, norm, &x, NULL);
+    if ((res = mp_div_2d (&x, norm, &x, NULL)) != MP_OKAY) {
+      goto LBL_Y;
+    }
     mp_exch (&x, d);
   }
 
diff --git a/bn_mp_dr_reduce.c b/bn_mp_dr_reduce.c
index 62e9612..7cfe462 100644
--- a/bn_mp_dr_reduce.c
+++ b/bn_mp_dr_reduce.c
@@ -82,7 +82,9 @@ top:
    * Each successive "recursion" makes the input smaller and smaller.
    */
   if (mp_cmp_mag (x, n) != MP_LT) {
-    (void)s_mp_sub(x, n, x);
+    if ((err = s_mp_sub(x, n, x)) != MP_OKAY) {
+      return err;
+    }
     goto top;
   }
   return MP_OKAY;
diff --git a/bn_mp_exteuclid.c b/bn_mp_exteuclid.c
index 3b0bb4a..624f81d 100644
--- a/bn_mp_exteuclid.c
+++ b/bn_mp_exteuclid.c
@@ -61,9 +61,9 @@ int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
 
    /* make sure U3 >= 0 */
    if (u3.sign == MP_NEG) {
-      (void)mp_neg(&u1, &u1);
-      (void)mp_neg(&u2, &u2);
-      (void)mp_neg(&u3, &u3);
+       if ((err = mp_neg(&u1, &u1)) != MP_OKAY)                                   { goto _ERR; }
+       if ((err = mp_neg(&u2, &u2)) != MP_OKAY)                                   { goto _ERR; }
+       if ((err = mp_neg(&u3, &u3)) != MP_OKAY)                                   { goto _ERR; }
    }
 
    /* copy result out */
diff --git a/bn_mp_reduce_2k.c b/bn_mp_reduce_2k.c
index f03bc11..6abae6c 100644
--- a/bn_mp_reduce_2k.c
+++ b/bn_mp_reduce_2k.c
@@ -45,7 +45,9 @@ top:
    }
    
    if (mp_cmp_mag(a, n) != MP_LT) {
-      (void)s_mp_sub(a, n, a);
+      if ((res = s_mp_sub(a, n, a)) != MP_OKAY) {
+         goto ERR;
+      }
       goto top;
    }
    
diff --git a/bn_mp_reduce_2k_l.c b/bn_mp_reduce_2k_l.c
index 0ee5402..84198a3 100644
--- a/bn_mp_reduce_2k_l.c
+++ b/bn_mp_reduce_2k_l.c
@@ -46,7 +46,9 @@ top:
    }
    
    if (mp_cmp_mag(a, n) != MP_LT) {
-      (void)s_mp_sub(a, n, a);
+      if ((res = s_mp_sub(a, n, a)) != MP_OKAY) {
+         goto ERR;
+      }
       goto top;
    }
    
diff --git a/bn_mp_toom_mul.c b/bn_mp_toom_mul.c
index 81fec9f..e2a4ac8 100644
--- a/bn_mp_toom_mul.c
+++ b/bn_mp_toom_mul.c
@@ -46,7 +46,9 @@ int mp_toom_mul(mp_int *a, mp_int *b, mp_int *c)
        goto ERR;
     }
     mp_rshd(&a1, B);
-    (void)mp_mod_2d(&a1, DIGIT_BIT * B, &a1);
+    if ((res = mp_mod_2d(&a1, DIGIT_BIT * B, &a1)) != MP_OKAY) {
+       goto ERR;
+    }
 
     if ((res = mp_copy(a, &a2)) != MP_OKAY) {
        goto ERR;
diff --git a/bn_mp_toom_sqr.c b/bn_mp_toom_sqr.c
index d2c096c..0fe967b 100644
--- a/bn_mp_toom_sqr.c
+++ b/bn_mp_toom_sqr.c
@@ -39,7 +39,9 @@ mp_toom_sqr(mp_int *a, mp_int *b)
        goto ERR;
     }
     mp_rshd(&a1, B);
-    (void)mp_mod_2d(&a1, DIGIT_BIT * B, &a1);
+    if ((res = mp_mod_2d(&a1, DIGIT_BIT * B, &a1)) != MP_OKAY) {
+       goto ERR;
+    }
 
     if ((res = mp_copy(a, &a2)) != MP_OKAY) {
        goto ERR;