commit 1d114d2efa76ba77a4fa256bca4e412f32b611ac
author Janos Follath <janos.follath@arm.com> Thu Feb 11 11:08:18 2016 +0000
committer Simon Butcher <simon.butcher@arm.com> Wed Mar 16 23:29:30 2016 +0000
tree c2cbad8cf13f9d53ad068f0905f1ab66ce4d1aa6
parent 45a5f7406de50a6e2dac0289009a2d19ea9c0798

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
      */