[msitools] Only set property type once it’s safe

[Marc-Andre Lureau <malureau src gnome org>]

commit 4bdbe225d10f06e8f9442c0213edd78bd4a13ab2
Author: Stephen Kitt <steve sk2 org>
Date:   Thu Jul 20 21:34:08 2017 +0200

    Only set property type once it’s safe
    
    Setting the property type before we know the property is valid leaves
    libmsi vulnerable to invalid frees: a bad string property sets the
    type, then we notice the string is invalid, and during clean-up
    attempt to free an invalid pointer.
    
    Crash discovered by Jakub Wilk, https://bugs.debian.org/869082
    
    Signed-off-by: Stephen Kitt <steve sk2 org>

 libmsi/libmsi-summary-info.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/libmsi/libmsi-summary-info.c b/libmsi/libmsi-summary-info.c
index 081b50c..8ac6b33 100644
--- a/libmsi/libmsi-summary-info.c
+++ b/libmsi/libmsi-summary-info.c
@@ -353,7 +353,6 @@ static void read_properties_from_data( LibmsiOLEVariant *prop, const uint8_t *da
             break;
         }
 
-        property->vt = proptype;
         switch(proptype)
         {
         case OLEVT_I2:
@@ -409,6 +408,9 @@ static void read_properties_from_data( LibmsiOLEVariant *prop, const uint8_t *da
             g_critical("invalid type \n");
             break;
         }
+
+        /* Now we now the type is valid, store it */
+        property->vt = proptype;
     }
 }