From d59948a1714fe32729c77e3ea54e0992d48e8541 Mon Sep 17 00:00:00 2001
From: Matt Sarett <msarett@google.com>
Date: Wed, 26 Apr 2017 10:59:48 -0400
Subject: SkPngCodec: Do not return kInvalidConversion on corrupt png

In this case, the fuzzer thinks there is a bug because we are
returning kInvalidConversion for a corrupt png file.

Bug: skia:6550
Change-Id: I33f588442f5eaa8a4d642e9328750779f9a9ef5d
Reviewed-on: https://skia-review.googlesource.com/14324
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
---
 src/codec/SkPngCodec.cpp | 32 +++++++++++++++++++-------------
 src/codec/SkPngCodec.h   |  4 ++--
 2 files changed, 21 insertions(+), 15 deletions(-)

(limited to 'src/codec')

diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp
index b6f418fd49..1c5f821c65 100644
--- a/src/codec/SkPngCodec.cpp
+++ b/src/codec/SkPngCodec.cpp
@@ -986,11 +986,11 @@ void SkPngCodec::destroyReadStruct() {
 // Getting the pixels
 ///////////////////////////////////////////////////////////////////////////////
 
-bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& options,
-                                  SkPMColor ctable[], int* ctableCount) {
+SkCodec::Result SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& options,
+                                             SkPMColor ctable[], int* ctableCount) {
     if (setjmp(PNG_JMPBUF((png_struct*)fPng_ptr))) {
         SkCodecPrintf("Failed on png_read_update_info.\n");
-        return false;
+        return kInvalidInput;
     }
     png_read_update_info(fPng_ptr, fInfo_ptr);
 
@@ -999,7 +999,7 @@ bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& opt
     fSwizzler.reset(nullptr);
 
     if (!this->initializeColorXform(dstInfo, options.fPremulBehavior)) {
-        return false;
+        return kInvalidConversion;
     }
 
     // If SkColorSpaceXform directly supports the encoded PNG format, we should skip format
@@ -1020,12 +1020,12 @@ bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& opt
     }
     if (skipFormatConversion && !options.fSubset) {
         fXformMode = kColorOnly_XformMode;
-        return true;
+        return kSuccess;
     }
 
     if (SkEncodedInfo::kPalette_Color == this->getEncodedInfo().color()) {
         if (!this->createColorTable(dstInfo, ctableCount)) {
-            return false;
+            return kInvalidInput;
         }
     }
 
@@ -1033,7 +1033,7 @@ bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& opt
     copy_color_table(dstInfo, fColorTable.get(), ctable, ctableCount);
 
     this->initializeSwizzler(dstInfo, options, skipFormatConversion);
-    return true;
+    return kSuccess;
 }
 
 void SkPngCodec::initializeXformParams() {
@@ -1115,12 +1115,15 @@ SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst,
                                         size_t rowBytes, const Options& options,
                                         SkPMColor ctable[], int* ctableCount,
                                         int* rowsDecoded) {
-    if (!conversion_possible(dstInfo, this->getInfo()) ||
-        !this->initializeXforms(dstInfo, options, ctable, ctableCount))
-    {
+    if (!conversion_possible(dstInfo, this->getInfo())) {
         return kInvalidConversion;
     }
 
+    Result result = this->initializeXforms(dstInfo, options, ctable, ctableCount);
+    if (kSuccess != result) {
+        return result;
+    }
+
     if (options.fSubset) {
         return kUnimplemented;
     }
@@ -1133,12 +1136,15 @@ SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst,
 SkCodec::Result SkPngCodec::onStartIncrementalDecode(const SkImageInfo& dstInfo,
         void* dst, size_t rowBytes, const SkCodec::Options& options,
         SkPMColor* ctable, int* ctableCount) {
-    if (!conversion_possible(dstInfo, this->getInfo()) ||
-        !this->initializeXforms(dstInfo, options, ctable, ctableCount))
-    {
+    if (!conversion_possible(dstInfo, this->getInfo())) {
         return kInvalidConversion;
     }
 
+    Result result = this->initializeXforms(dstInfo, options, ctable, ctableCount);
+    if (kSuccess != result) {
+        return result;
+    }
+
     this->allocateStorage(dstInfo);
 
     int firstRow, lastRow;
diff --git a/src/codec/SkPngCodec.h b/src/codec/SkPngCodec.h
index 4809723db6..d729fb11da 100644
--- a/src/codec/SkPngCodec.h
+++ b/src/codec/SkPngCodec.h
@@ -103,8 +103,8 @@ private:
 
     bool createColorTable(const SkImageInfo& dstInfo, int* ctableCount);
     // Helper to set up swizzler, color xforms, and color table. Also calls png_read_update_info.
-    bool initializeXforms(const SkImageInfo& dstInfo, const Options&, SkPMColor* colorPtr,
-                          int* colorCount);
+    SkCodec::Result initializeXforms(const SkImageInfo& dstInfo, const Options&,
+                                     SkPMColor* colorPtr, int* colorCount);
     void initializeSwizzler(const SkImageInfo& dstInfo, const Options&, bool skipFormatConversion);
     void allocateStorage(const SkImageInfo& dstInfo);
     void destroyReadStruct();
-- 
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