[msitools: 2/6] libmsi: treat property as invalid if str len is 0

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

commit 7a5c88906c9383d6cc9200a9d402e9977f2ef99c
Author: Marc-André Lureau <marcandre lureau redhat com>
Date:   Tue Mar 16 12:52:55 2021 +0400

    libmsi: treat property as invalid if str len is 0
    
    Fixes #34 "Integer overflow in read_properties_from_data"
    
    Signed-off-by: Marc-André Lureau <marcandre lureau redhat com>

 libmsi/libmsi-summary-info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/libmsi/libmsi-summary-info.c b/libmsi/libmsi-summary-info.c
index 27b1e2e..2ecc4f8 100644
--- a/libmsi/libmsi-summary-info.c
+++ b/libmsi/libmsi-summary-info.c
@@ -372,7 +372,7 @@ static void read_properties_from_data( LibmsiOLEVariant *prop, const uint8_t *da
             break;
         case OLEVT_LPSTR:
             len = read_dword(data, &dwOffset);
-            if( dwOffset + len > sz )
+            if(len == 0 || dwOffset + len > sz )
             {
                 g_critical("not enough data for type %d %d %d \n", dwOffset, len, sz);
                 valid = FALSE;