From ffec86ed5010c5a2be14f47b33bcf4ed3169a199 Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Mon, 13 Jul 2015 00:33:40 -0400
Subject: [PATCH] pixops: Be more careful about integer overflow

Our loader code is supposed to handle out-of-memory and overflow
situations gracefully, reporting errors instead of aborting. But
if you load an image at a specific size, we also execute our
scaling code, which was not careful enough about overflow in some
places.

This commit makes the scaling code silently return if it fails to
allocate filter tables. This is the best we can do, since
gdk_pixbuf_scale() is not taking a GError.

https://bugzilla.gnome.org/show_bug.cgi?id=752297
---
 gdk-pixbuf/pixops/pixops.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/gdk-pixbuf/pixops/pixops.c b/gdk-pixbuf/pixops/pixops.c
index 29a1c14..ce51745 100644
--- a/gdk-pixbuf/pixops/pixops.c
+++ b/gdk-pixbuf/pixops/pixops.c
@@ -1272,7 +1272,16 @@ make_filter_table (PixopsFilter *filter)
   int i_offset, j_offset;
   int n_x = filter->x.n;
   int n_y = filter->y.n;
-  int *weights = g_new (int, SUBSAMPLE * SUBSAMPLE * n_x * n_y);
+  gsize n_weights;
+  int *weights;
+
+  n_weights = SUBSAMPLE * SUBSAMPLE * n_x * n_y;
+  if (n_weights / (SUBSAMPLE * SUBSAMPLE * n_x) != n_y)
+    return NULL; /* overflow, bail */
+
+  weights = g_try_new (int, n_weights);
+  if (!weights)
+    return NULL; /* overflow, bail */
 
   for (i_offset=0; i_offset < SUBSAMPLE; i_offset++)
     for (j_offset=0; j_offset < SUBSAMPLE; j_offset++)
@@ -1347,8 +1356,11 @@ pixops_process (guchar         *dest_buf,
   if (x_step == 0 || y_step == 0)
     return; /* overflow, bail out */
 
-  line_bufs = g_new (guchar *, filter->y.n);
   filter_weights = make_filter_table (filter);
+  if (!filter_weights)
+    return; /* overflow, bail out */
+
+  line_bufs = g_new (guchar *, filter->y.n);
 
   check_shift = check_size ? get_check_shift (check_size) : 0;
 
@@ -1468,7 +1480,7 @@ tile_make_weights (PixopsFilterDimension *dim,
 		   double                 scale)
 {
   int n = ceil (1 / scale + 1);
-  double *pixel_weights = g_new (double, SUBSAMPLE * n);
+  double *pixel_weights = g_malloc_n (sizeof (double) * SUBSAMPLE, n);
   int offset;
   int i;
 
@@ -1526,7 +1538,7 @@ bilinear_magnify_make_weights (PixopsFilterDimension *dim,
     }
 
   dim->n = n;
-  dim->weights = g_new (double, SUBSAMPLE * n);
+  dim->weights = g_malloc_n (sizeof (double) * SUBSAMPLE, n);
 
   pixel_weights = dim->weights;
 
@@ -1617,7 +1629,7 @@ bilinear_box_make_weights (PixopsFilterDimension *dim,
 			   double                 scale)
 {
   int n = ceil (1/scale + 3.0);
-  double *pixel_weights = g_new (double, SUBSAMPLE * n);
+  double *pixel_weights = g_malloc_n (sizeof (double) * SUBSAMPLE, n);
   double w;
   int offset, i;
 
-- 
2.5.0