Moved md_init_ctx() calls around to minimize exit points

library/rsa.c

@@ -441,8 +441,6 @@ int rsa_pkcs1_encrypt( rsa_context *ctx,
 
             memset( output, 0, olen );
 
-            md_init_ctx( &md_ctx, md_info );
-
             *p++ = 0;
 
             // Generate a random octet string seed
@@ -460,6 +458,8 @@ int rsa_pkcs1_encrypt( rsa_context *ctx,
             *p++ = 1;
             memcpy( p, input, ilen ); 
 
+            md_init_ctx( &md_ctx, md_info );
+
             // maskedDB: Apply dbMask to DB
             //
             mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,  
@@ -800,8 +800,6 @@ int rsa_pkcs1_sign( rsa_context *ctx,
 
             memset( sig, 0, olen );
 
-            md_init_ctx( &md_ctx, md_info );
-
             msb = mpi_msb( &ctx->N ) - 1;
 
             // Generate salt of length slen
@@ -817,6 +815,8 @@ int rsa_pkcs1_sign( rsa_context *ctx,
             memcpy( p, salt, slen );
             p += slen;
 
+            md_init_ctx( &md_ctx, md_info );
+
             // Generate H = Hash( M' )
             //
             md_starts( &md_ctx );
@@ -1016,8 +1016,6 @@ int rsa_pkcs1_verify( rsa_context *ctx,
 
             memset( zeros, 0, 8 );
 
-            md_init_ctx( &md_ctx, md_info );
-
             // Note: EMSA-PSS verification is over the length of N - 1 bits
             //
             msb = mpi_msb( &ctx->N ) - 1;
@@ -1032,6 +1030,8 @@ int rsa_pkcs1_verify( rsa_context *ctx,
             if( buf[0] >> ( 8 - siglen * 8 + msb ) )
                 return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
 
+            md_init_ctx( &md_ctx, md_info );
+
             mgf_mask( p, siglen - hlen - 1, p + siglen - hlen - 1, hlen, &md_ctx );
 
             buf[0] &= 0xFF >> ( siglen * 8 - msb );
@@ -1039,11 +1039,12 @@ int rsa_pkcs1_verify( rsa_context *ctx,
             while( *p == 0 && p < buf + siglen )
                 p++;
 
-            if( p == buf + siglen )
-                return( POLARSSL_ERR_RSA_INVALID_PADDING );
-
-            if( *p++ != 0x01 )
+            if( p == buf + siglen ||
+                *p++ != 0x01 )
+            {
+                md_free_ctx( &md_ctx );
                 return( POLARSSL_ERR_RSA_INVALID_PADDING );
+            }
 
             slen -= p - buf;