commit 0057ac11fccc82bc5b0c1bb0aefe838cc04efd13
author scroggo <scroggo@chromium.org> Tue Oct 25 12:48:25 2016 -0700
committer Commit bot <commit-bot@chromium.org> Tue Oct 25 12:48:25 2016 -0700
tree d75089631c34819ae1f6b94ff312f77fa4d43dc6
parent e9db0b7f0e9185c04e54b53f65a882958be3394c

Always use a color table with 256 colors

Speculative fix for skbug.com/5883

We are hitting an assert (which I have not been able to repro - still
need to get the skp that triggers it) because we are trying to read
beyond the end of the color table. We use 8-bit indices, so 256 should
be enough to prevent going beyond the end. There is only one case when
we use a smaller color table - when it is a dummy. Make the dummy full
size.

NOTREECHECKS=true

BUG=skia:5883
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2452673002

Review-Url: https://codereview.chromium.org/2452673002

src/codec/SkGifCodec.cpp

diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index 263004b..e55f6f3 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -37,6 +37,7 @@
 #include "SkGifCodec.h"
 #include "SkStream.h"
 #include "SkSwizzler.h"
+#include "SkUtils.h"
 
 #include <algorithm>
 
@@ -143,9 +144,10 @@
     fCurrColorTable = fReader->getColorTable(dstInfo.colorType(), frameIndex);
     fCurrColorTableIsReal = fCurrColorTable;
     if (!fCurrColorTable) {
-        // This is possible for an empty frame. Create a dummy with one value (transparent).
-        SkPMColor color = SK_ColorTRANSPARENT;
-        fCurrColorTable.reset(new SkColorTable(&color, 1));
+        // This is possible for an empty frame. Create a dummy with all transparent.
+        SkPMColor colors[MAX_COLORS];
+        sk_memset32(colors, SK_ColorTRANSPARENT, MAX_COLORS);
+        fCurrColorTable.reset(new SkColorTable(colors, 256));
     }
 
     if (inputColorCount) {