Fix overflow caught by ASAN.

src/codec/SkBmpCodec.cpp

Index: src/codec/SkBmpCodec.cpp
diff --git a/src/codec/SkBmpCodec.cpp b/src/codec/SkBmpCodec.cpp
index 191c2ad8009cbc39e713a2a56452e632a7e84012..2e9eca9fe49714fe665af6f6d8c96a18d3d07823 100644
--- a/src/codec/SkBmpCodec.cpp
+++ b/src/codec/SkBmpCodec.cpp
@@ -554,7 +554,7 @@ int32_t SkBmpCodec::getDstRow(int32_t y, int32_t height) const {
 uint32_t SkBmpCodec::computeNumColors(uint32_t numColors) {
     // Zero is a default for maxColors
     // Also set numColors to maxColors when it is too large
-    uint32_t maxColors = 1 << fBitsPerPixel;
+    uint32_t maxColors = fBitsPerPixel >= 32 ? UINT32_MAX : 1 << fBitsPerPixel;

[msarett, 2015/12/03 20:55:22]

Can we use 0 instead of UINT32_MAX?  While you're right that this value is only
used when fBitsPerPixel <= 8 (meaning there is a color table), I'd hate to think
that we *might* try to make a color table with UINT32_MAX colors.

This fix is perfect for now, but in the longer term, we should consider only
calling this function when there actually is a color table.

     if (numColors == 0 || numColors >= maxColors) {
         return maxColors;
     }