diff -urNp old/plug-ins/common/file-psp.c new/plug-ins/common/file-psp.c

--- old/plug-ins/common/file-psp.c	2018-01-04 12:04:14.636811394 +0100

+++ new/plug-ins/common/file-psp.c	2018-01-04 12:12:41.717877789 +0100

@@ -1777,6 +1777,15 @@ load_image (const gchar  *filename,

     {

       block_start = ftell (f);

+      if (block_start + block_total_len > st.st_size)

+        {

+          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,

+                       _("Could not open '%s' for reading: %s"),

+                       gimp_filename_to_utf8 (filename),

+                       _("invalid block size"));

+          goto error;

+        }

+

       if (id == PSP_IMAGE_BLOCK)

         {

           if (block_number != 0)