X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=crypto%2Fbn%2Fbn_gf2m.c;h=dea1fd3b873c66d758aac81f2c9a7e88721eb503;hp=8bd17e0e7c9acc4094856232c0567f2c00f46242;hb=c237de058f91072b5d54ad9c570049c14df6957e;hpb=e2aeb8174bd11c3dff2861fb6e1afa4c04587b19

diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index 8bd17e0e7c..dea1fd3b87 100644
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/bn/bn_gf2m.c
@@ -370,12 +370,16 @@ int BN_GF2m_mod_arr(BIGNUM *r, const BIGNUM *a, const unsigned int p[])
 
 		for (k = 1; p[k] > 0; k++)
 			{
+			BN_ULONG tmp_ulong;
+
 			/* reducing component t^p[k]*/
 			n = p[k] / BN_BITS2;   
 			d0 = p[k] % BN_BITS2;
 			d1 = BN_BITS2 - d0;
 			z[n] ^= (zz << d0);
-			if (d0) z[n+1] ^= (zz >> d1);
+			tmp_ulong = zz >> d1;
+                        if (d0 && tmp_ulong)
+                                z[n+1] ^= tmp_ulong;
 			}