minor bug in EVP_DecryptFinal_ex

[K S Sreeram]

when block padding is used, byte value 0 can never
be the final byte of the padded plain text, the only
valid range is [1 .. block_size].
The check for 0 is not performed when detecting
malformed padding in EVP_DecryptFinal_ex.
I've attached the one-line patch for this.

regards
Sreeram

diff -ur openssl-0.9.8-orig/crypto/evp/evp_enc.c 
openssl-0.9.8/crypto/evp/evp_enc.c
--- openssl-0.9.8-orig/crypto/evp/evp_enc.c     2005-05-11 09:15:30.000000000 
+0530
+++ openssl-0.9.8/crypto/evp/evp_enc.c  2005-07-19 01:27:38.378272000 +0530
@@ -449,7 +449,7 @@
                        }
                OPENSSL_assert(b <= sizeof ctx->final);
                n=ctx->final[b-1];
-               if (n > (int)b)
+               if ( (n == 0) || (n > (int)b) )
                        {
                        EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_BAD_DECRYPT);
                        return(0);