avoid potential infinite loop in final reduction round of BN_GF2m_mod_arr()
Submitted by: Huang Ying
Reviewed by: Douglas Stebila
diff --git a/CHANGES b/CHANGES
index b0359e5..f2e4487 100644
--- a/CHANGES
+++ b/CHANGES
@@ -702,12 +702,16 @@
Changes between 0.9.8h and 0.9.8i [xx XXX xxxx]
+ *) Fix BN_GF2m_mod_arr() top-bit cleanup code.
+ [Huang Ying]
+
*) Expand ENGINE to support engine supplied SSL client certificate functions.
This work was sponsored by Logica.
[Steve Henson]
- *) Add CryptoAPI ENGINE to support use of RSA and DSA keys held in Windows keystores. Support for SSL/TLS client authentication too.
+ *) Add CryptoAPI ENGINE to support use of RSA and DSA keys held in Windows
+ keystores. Support for SSL/TLS client authentication too.
Not compiled unless enable-capieng specified to Configure.
This work was sponsored by Logica.
diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index be409e1..f7551da 100644
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/bn/bn_gf2m.c
@@ -322,7 +322,11 @@
if (zz == 0) break;
d1 = BN_BITS2 - d0;
- if (d0) z[dN] = (z[dN] << d1) >> d1; /* clear up the top d1 bits */
+ /* clear up the top d1 bits */
+ if (d0)
+ z[dN] = (z[dN] << d1) >> d1;
+ else
+ z[dN] = 0;
z[0] ^= zz; /* reduction t^0 component */
for (k = 1; p[k] != 0; k++)
