commit fb9d33047a0632eed2c8092ef615eb12d4982f50
author Janos Follath <janos.follath@arm.com> Thu Feb 11 11:08:18 2016 +0000
committer Simon Butcher <simon.butcher@arm.com> Sat Apr 09 00:16:40 2016 +0100
tree e37acca6483ef5a1ff04713b3238f1762f1182a8
parent 532d62f900c6d3fecf0b3e0169f76e1f667d2a1f

Move underflow test to make time constant

library/rsa.c

diff --git a/library/rsa.c b/library/rsa.c
index 6f65218..5463500 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -695,6 +695,12 @@
     if( md_info == NULL )
         return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
 
+    hlen = mbedtls_md_get_size( md_info );
+
+    // checking for integer underflow
+    if( 2 * hlen + 2 > ilen )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
     /*
      * RSA operation
      */