1 files changed, 11 insertions, 16 deletions

diff --git a/src/lib/libcrypto/bn/bn_shift.c b/src/lib/libcrypto/bn/bn_shift.c
index 944bf1794b..70f785ea18 100644
--- a/src/lib/libcrypto/bn/bn_shift.c
+++ b/src/lib/libcrypto/bn/bn_shift.c
@@ -60,9 +60,7 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
-int BN_lshift1(r, a)
-BIGNUM *r;
-BIGNUM *a;
+int BN_lshift1(BIGNUM *r, const BIGNUM *a)
         {
         register BN_ULONG *ap,*rp,t,c;
         int i;
@@ -94,9 +92,7 @@ BIGNUM *a;
         return(1);
         }
 
-int BN_rshift1(r, a)
-BIGNUM *r;
-BIGNUM *a;
+int BN_rshift1(BIGNUM *r, const BIGNUM *a)
         {
         BN_ULONG *ap,*rp,t,c;
         int i;
@@ -125,18 +121,15 @@ BIGNUM *a;
         return(1);
         }
 
-int BN_lshift(r, a, n)
-BIGNUM *r;
-BIGNUM *a;
-int n;
+int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
         {
         int i,nw,lb,rb;
         BN_ULONG *t,*f;
         BN_ULONG l;
 
         r->neg=a->neg;
-        if (bn_wexpand(r,a->top+(n/BN_BITS2)+1) == NULL) return(0);
         nw=n/BN_BITS2;
+        if (bn_wexpand(r,a->top+nw+1) == NULL) return(0);
         lb=n%BN_BITS2;
         rb=BN_BITS2-lb;
         f=a->d;
@@ -160,10 +153,7 @@ int n;
         return(1);
         }
 
-int BN_rshift(r, a, n)
-BIGNUM *r;
-BIGNUM *a;
-int n;
+int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
         {
         int i,j,nw,lb,rb;
         BN_ULONG *t,*f;
@@ -172,7 +162,7 @@ int n;
         nw=n/BN_BITS2;
         rb=n%BN_BITS2;
         lb=BN_BITS2-rb;
-        if (nw > a->top)
+        if (nw > a->top || a->top == 0)
                 {
                 BN_zero(r);
                 return(1);
@@ -182,6 +172,11 @@ int n;
                 r->neg=a->neg;
                 if (bn_wexpand(r,a->top-nw+1) == NULL) return(0);
                 }
+        else
+                {
+                if (n == 0)
+                        return 1; /* or the copying loop will go berserk */
+                }
 
         f= &(a->d[nw]);
         t=r->d;