[gimp/gimp-2-10] Issue #1792 - Xcf file crashing gimp-console-2.10 ...

[Ell <ell src gnome org>]

commit 2ac529cb8ccdcbcedf949036702b1fd81719eb91
Author: Ell <ell_se yahoo com>
Date:   Fri Jul 6 13:00:35 2018 -0400

    Issue #1792 - Xcf file crashing gimp-console-2.10 ...
    
    ... (valgrind reports Invalid read)
    
    Add gimp_babl_is_valid(), which takes a GimpImageBaseType and a
    GimpPrecision, and determines whether the image-type/precision
    combination is valid.  Use this function to validate that loaded
    XCFs use a valid type/precision combination, before trying to
    create the image.  Otherwise, we get a CRITICAL, and eventually a
    segfault, when the combination is invalid.
    
    Use the same function to validate the arguments of
    gimp_image_new().
    
    (cherry picked from commit a0a62656d2d562649414bb4f93d58bda52d7157b)

 app/core/gimpimage.c |  3 +--
 app/gegl/gimp-babl.c | 24 ++++++++++++++++++++++++
 app/gegl/gimp-babl.h |  3 +++
 app/xcf/xcf-load.c   |  9 +++++++++
 4 files changed, 37 insertions(+), 2 deletions(-)
---
diff --git a/app/core/gimpimage.c b/app/core/gimpimage.c
index 7f89c48900..1f09c89f57 100644
--- a/app/core/gimpimage.c
+++ b/app/core/gimpimage.c
@@ -1703,8 +1703,7 @@ gimp_image_new (Gimp              *gimp,
                 GimpPrecision      precision)
 {
   g_return_val_if_fail (GIMP_IS_GIMP (gimp), NULL);
-  g_return_val_if_fail (base_type != GIMP_INDEXED ||
-                        precision == GIMP_PRECISION_U8_GAMMA, NULL);
+  g_return_val_if_fail (gimp_babl_is_valid (base_type, precision), NULL);
 
   return g_object_new (GIMP_TYPE_IMAGE,
                        "gimp",      gimp,
diff --git a/app/gegl/gimp-babl.c b/app/gegl/gimp-babl.c
index 129d53e265..a2093cb401 100644
--- a/app/gegl/gimp-babl.c
+++ b/app/gegl/gimp-babl.c
@@ -755,6 +755,30 @@ gimp_babl_precision (GimpComponentType component,
   g_return_val_if_reached (-1);
 }
 
+gboolean
+gimp_babl_is_valid (GimpImageBaseType base_type,
+                    GimpPrecision     precision)
+{
+  switch (base_type)
+    {
+    case GIMP_RGB:
+    case GIMP_GRAY:
+      return TRUE;
+
+    case GIMP_INDEXED:
+      switch (precision)
+        {
+        case GIMP_PRECISION_U8_GAMMA:
+          return TRUE;
+
+        default:
+          return FALSE;
+        }
+    }
+
+  g_return_val_if_reached (FALSE);
+}
+
 const Babl *
 gimp_babl_format (GimpImageBaseType  base_type,
                   GimpPrecision      precision,
diff --git a/app/gegl/gimp-babl.h b/app/gegl/gimp-babl.h
index 7a9e1c30a8..2fe6ba6f0f 100644
--- a/app/gegl/gimp-babl.h
+++ b/app/gegl/gimp-babl.h
@@ -38,6 +38,9 @@ gboolean            gimp_babl_linear           (GimpPrecision      precision);
 GimpPrecision       gimp_babl_precision        (GimpComponentType  component,
                                                 gboolean           linear);
 
+gboolean            gimp_babl_is_valid         (GimpImageBaseType  base_type,
+                                                GimpPrecision      precision);
+
 const Babl        * gimp_babl_format           (GimpImageBaseType  base_type,
                                                 GimpPrecision      precision,
                                                 gboolean           with_alpha);
diff --git a/app/xcf/xcf-load.c b/app/xcf/xcf-load.c
index 3f15ca127a..b5ffc06cec 100644
--- a/app/xcf/xcf-load.c
+++ b/app/xcf/xcf-load.c
@@ -31,6 +31,7 @@
 
 #include "config/gimpcoreconfig.h"
 
+#include "gegl/gimp-babl.h"
 #include "gegl/gimp-gegl-tile-compat.h"
 
 #include "core/gimp.h"
@@ -220,6 +221,14 @@ xcf_load_image (Gimp     *gimp,
   GIMP_LOG (XCF, "version=%d, width=%d, height=%d, image_type=%d, precision=%d",
             info->file_version, width, height, image_type, precision);
 
+  if (! gimp_babl_is_valid (image_type, precision))
+    {
+      gimp_message_literal (gimp, G_OBJECT (info->progress),
+                            GIMP_MESSAGE_ERROR,
+                            _("Invalid image mode and precision combination."));
+      goto hard_error;
+    }
+
   image = gimp_create_image (gimp, width, height, image_type, precision,
                              FALSE);