From 88c9657960a6c5d3673a25c266781e876c181add Mon Sep 17 00:00:00 2001
From: Hector Marco-Gisbert <hecmargi@upv.es>
Date: Fri, 13 Nov 2015 16:21:09 +0100
Subject: [PATCH] Fix security issue when reading username and password

  This patch fixes two integer underflows at:
    * grub-core/lib/crypto.c
    * grub-core/normal/auth.c

Signed-off-by: Hector Marco-Gisbert <hecmargi@upv.es>
Signed-off-by: Ismael Ripoll-Ripoll <iripoll@disca.upv.es>
---
 grub-core/lib/crypto.c  | 2 +-
 grub-core/normal/auth.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/grub-core/lib/crypto.c b/grub-core/lib/crypto.c
index 010e550..524a3d8 100644
--- a/grub-core/lib/crypto.c
+++ b/grub-core/lib/crypto.c
@@ -468,7 +468,7 @@ grub_password_get (char buf[], unsigned buf_size)
 	  break;
 	}
 
-      if (key == '\b')
+      if (key == '\b' && cur_len)
 	{
 	  cur_len--;
 	  continue;
diff --git a/grub-core/normal/auth.c b/grub-core/normal/auth.c
index c6bd96e..5782ec5 100644
--- a/grub-core/normal/auth.c
+++ b/grub-core/normal/auth.c
@@ -172,7 +172,7 @@ grub_username_get (char buf[], unsigned buf_size)
 	  break;
 	}
 
-      if (key == '\b')
+      if (key == '\b' && cur_len)
 	{
 	  cur_len--;
 	  grub_printf ("\b");
-- 
1.9.1

