[tor-commits] [tor-browser/tor-browser-68.12.0esr-9.5-1] Bug 1672223 - [sfnt] Fix heap buffer overflow. r=jfkthame

[sysrqb@xxxxxxxxxxxxxx]

commit 324751877ea62d526cfda8e581a4ba1a1f431769
Author: Werner Lemberg <wl@xxxxxxx>
Date:   Tue Oct 20 19:56:59 2020 +0000

    Bug 1672223 - [sfnt] Fix heap buffer overflow. r=jfkthame
    
    This is CVE-2020-15999.
    
    * src/sfnt/pngshim.c (Load_SBit_Png): Test bitmap size earlier.
    
    Differential Revision: https://phabricator.services.mozilla.com/D94153
---
 modules/freetype2/src/sfnt/pngshim.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/modules/freetype2/src/sfnt/pngshim.c b/modules/freetype2/src/sfnt/pngshim.c
index 16020266afd5..7d856af53922 100644
--- a/modules/freetype2/src/sfnt/pngshim.c
+++ b/modules/freetype2/src/sfnt/pngshim.c
@@ -327,6 +327,13 @@
 
     if ( populate_map_and_metrics )
     {
+      /* reject too large bitmaps similarly to the rasterizer */
+      if ( imgHeight > 0x7FFF || imgWidth > 0x7FFF )
+      {
+        error = FT_THROW( Array_Too_Large );
+        goto DestroyExit;
+      }
+
       metrics->width  = (FT_UShort)imgWidth;
       metrics->height = (FT_UShort)imgHeight;
 
@@ -335,13 +342,6 @@
       map->pixel_mode = FT_PIXEL_MODE_BGRA;
       map->pitch      = (int)( map->width * 4 );
       map->num_grays  = 256;
-
-      /* reject too large bitmaps similarly to the rasterizer */
-      if ( map->rows > 0x7FFF || map->width > 0x7FFF )
-      {
-        error = FT_THROW( Array_Too_Large );
-        goto DestroyExit;
-      }
     }
 
     /* convert palette/gray image to rgb */

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