[librsvg] bgo#777155 - Ignore patterns that have close-to-zero dimensions

[Federico Mena Quintero <federico src gnome org>]

commit 45d855f82ba6ddaa534f42ee22783a90955bb160
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Jan 11 15:33:31 2017 -0600

    bgo#777155 - Ignore patterns that have close-to-zero dimensions
    
    A fuzzed file yielded a pattern that had (0, 0) for a pattern's width
    and height.  We try to invert a scaling matrix based on those
    dimensions; this would fail for such a pattern.  Now we ignore patterns
    that have unspecified dimensions, or that are very close to zero.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777155

 rsvg-cairo-draw.c                                  |   13 ++++--
 .../render-crash/777155-zero-sized-pattern.svg     |   50 ++++++++++++++++++++
 2 files changed, 59 insertions(+), 4 deletions(-)
---
diff --git a/rsvg-cairo-draw.c b/rsvg-cairo-draw.c
index 4fd9f36..f2c76cf 100644
--- a/rsvg-cairo-draw.c
+++ b/rsvg-cairo-draw.c
@@ -180,6 +180,7 @@ _set_source_rsvg_pattern (RsvgDrawingCtx * ctx,
     cairo_matrix_t affine, caffine, taffine;
     double bbwscale, bbhscale, scwscale, schscale;
     double patternw, patternh, patternx, patterny;
+    double scaled_width, scaled_height;
     int pw, ph;
 
     rsvg_pattern = &local_pattern;
@@ -197,10 +198,8 @@ _set_source_rsvg_pattern (RsvgDrawingCtx * ctx,
     if (rsvg_pattern->obj_bbox)
         rsvg_drawing_ctx_pop_view_box (ctx);
 
-
     /* Work out the size of the rectangle so it takes into account the object bounding box */
 
-
     if (rsvg_pattern->obj_bbox) {
         bbwscale = bbox.rect.width;
         bbhscale = bbox.rect.height;
@@ -217,8 +216,14 @@ _set_source_rsvg_pattern (RsvgDrawingCtx * ctx,
     pw = patternw * bbwscale * scwscale;
     ph = patternh * bbhscale * schscale;
 
-    scwscale = (double) pw / (double) (patternw * bbwscale);
-    schscale = (double) ph / (double) (patternh * bbhscale);
+    scaled_width = patternw * bbwscale;
+    scaled_height = patternh * bbhscale;
+
+    if (fabs (scaled_width) < DBL_EPSILON || fabs (scaled_height) < DBL_EPSILON)
+        return;
+
+    scwscale = pw / scaled_width;
+    schscale = ph / scaled_height;
 
     surface = cairo_surface_create_similar (cairo_get_target (cr_render),
                                             CAIRO_CONTENT_COLOR_ALPHA, pw, ph);
diff --git a/tests/fixtures/render-crash/777155-zero-sized-pattern.svg 
b/tests/fixtures/render-crash/777155-zero-sized-pattern.svg
new file mode 100644
index 0000000..1412da4
--- /dev/null
+++ b/tests/fixtures/render-crash/777155-zero-sized-pattern.svg
@@ -0,0 +1,50 @@
+<svg id="svgt" width="100%" height="100%" viewBox="0 0 480 3">
+  <!--======-->
+  <!--=    =-->
+  <!--=    =-->
+  <!--=    =-->
+  <!--=    =-->
+  <!--=    =-->
+  <!--======-->
+  <d:SVGTestCase s:d="httt" s="$R$">
+<d:testDescription x="hts">
+  <p>
+    </p>
+  <p>  </p>
+    </d:testDescription>
+<d:operatorScript xmlns="httl">
+  <p>Runed.</p>
+</d:operatorScript>
+<d:passCriteria s="html">
+  <p>
+  </p>
+    </d:passCriteria>
+  </d:SVGTestCase>
+  <title id="testle">$RC</title>
+  <defs>
+    <font-face   font-family=""
+  e="UF">
+  <font-face-src>
+    <f xliref="../cii"/>
+  </font-face-src>
+    </font-face>
+  </defs>
+  <g id="teent" font-family="SVf" font-size="18">
+    <defs>
+    <patterl id="Pattern1" patternUnits="userSpaceOnUse" width="100" height="100" viewBox="0 0 10 10" />
+    <pattern id="Pattern2" xlink:href="#Pattern1" />
+<pattern id="Pattern3" xlink:href="#Pattern2">
+    <circle cx="5" cy="5" r="2" fill="green"/>
+    </pattern> </defs> <circle cx="50" cy="50" r="20" fill="red" />
+    <rect fill="url(#Pattern3)" width="100" height="100" />
+  </g>
+  <g font-family="Sif" font-size="32">
+<text id="re0" stroke="none"   fill="black">ision: 1.3 $</text>
+  </g>
+  <rect id="te" x="1" y="1" width="478" height="358" fill="none" stroke="#000"/>
+  <!-- c-->
+  <g id="dra">
+    <rect x="1" y="1" width="478" height="20" fill="red" stroke="black" stroke-width="1"/>
+    <text font-family="SVG" font-weighR="bold" font-size="20"   text-anchor="middle" y="18" 
stroke-width="0.5" stroke="black" fill="white">DRAFT</text>
+  </g>
+</svg>