Bug 1224396 - Skia path allocation cleanups. r=msreckovic

MozReview-Commit-ID: GAf2vC1Fucv

gfx/skia/skia/include/core/SkPathRef.h

@@ -16,7 +16,7 @@
 #include "SkRRect.h"
 #include "SkRect.h"
 #include "SkRefCnt.h"
-#include <stddef.h> // ptrdiff_t
+#include "../private/SkTemplates.h"
 
 class SkRBuffer;
 class SkWBuffer;
@@ -433,31 +433,35 @@ private:
      */
     void makeSpace(size_t size) {
         SkDEBUGCODE(this->validate();)
-        ptrdiff_t growSize = size - fFreeSpace;
-        if (growSize <= 0) {
+        if (size <= fFreeSpace) {
             return;
         }
+        size_t growSize = size - fFreeSpace;
         size_t oldSize = this->currSize();
         // round to next multiple of 8 bytes
         growSize = (growSize + 7) & ~static_cast<size_t>(7);
         // we always at least double the allocation
-        if (static_cast<size_t>(growSize) < oldSize) {
+        if (growSize < oldSize) {
             growSize = oldSize;
         }
         if (growSize < kMinSize) {
             growSize = kMinSize;
         }
-        size_t newSize = oldSize + growSize;
+        constexpr size_t maxSize = std::numeric_limits<size_t>::max();
+        size_t newSize;
+        if (growSize <= maxSize - oldSize) {
+            newSize = oldSize + growSize;
+        } else {
+            SK_ABORT("Path too big.");
+        }
         // Note that realloc could memcpy more than we need. It seems to be a win anyway. TODO:
         // encapsulate this.
         fPoints = reinterpret_cast<SkPoint*>(sk_realloc_throw(fPoints, newSize));
         size_t oldVerbSize = fVerbCnt * sizeof(uint8_t);
-        void* newVerbsDst = reinterpret_cast<void*>(
-                                reinterpret_cast<intptr_t>(fPoints) + newSize - oldVerbSize);
-        void* oldVerbsSrc = reinterpret_cast<void*>(
-                                reinterpret_cast<intptr_t>(fPoints) + oldSize - oldVerbSize);
+        void* newVerbsDst = SkTAddOffset<void>(fPoints, newSize - oldVerbSize);
+        void* oldVerbsSrc = SkTAddOffset<void>(fPoints, oldSize - oldVerbSize);
         memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
-        fVerbs = reinterpret_cast<uint8_t*>(reinterpret_cast<intptr_t>(fPoints) + newSize);
+        fVerbs = SkTAddOffset<uint8_t>(fPoints, newSize);
         fFreeSpace += growSize;
         SkDEBUGCODE(this->validate();)
     }

gfx/skia/skia/src/core/SkArenaAlloc.cpp

@@ -8,6 +8,7 @@
 #include <algorithm>
 #include <cstddef>
 #include "SkArenaAlloc.h"
+#include "SkTypes.h"
 
 static char* end_chain(char*) { return nullptr; }
 
@@ -95,19 +96,31 @@ void SkArenaAlloc::ensureSpace(uint32_t size, uint32_t alignment) {
     // This must be conservative to add the right amount of extra memory to handle the alignment
     // padding.
     constexpr uint32_t alignof_max_align_t = 8;
-    uint32_t objSizeAndOverhead = size + headerSize + sizeof(Footer);
+    constexpr uint32_t maxSize = std::numeric_limits<uint32_t>::max();
+    constexpr uint32_t overhead = headerSize + sizeof(Footer);
+    SkASSERT_RELEASE(size <= maxSize - overhead);
+    uint32_t objSizeAndOverhead = size + overhead;
     if (alignment > alignof_max_align_t) {
-        objSizeAndOverhead += alignment - 1;
+        uint32_t alignmentOverhead = alignment - 1;
+        SkASSERT_RELEASE(objSizeAndOverhead <= maxSize - alignmentOverhead);
+        objSizeAndOverhead += alignmentOverhead;
     }
 
-    uint32_t allocationSize = std::max(objSizeAndOverhead, fExtraSize * fFib0);
-    fFib0 += fFib1;
-    std::swap(fFib0, fFib1);
+    uint32_t minAllocationSize;
+    if (fExtraSize <= maxSize / fFib0) {
+        minAllocationSize = fExtraSize * fFib0;
+        fFib0 += fFib1;
+        std::swap(fFib0, fFib1);
+    } else {
+        minAllocationSize = maxSize;
+    }
+    uint32_t allocationSize = std::max(objSizeAndOverhead, minAllocationSize);
 
     // Round up to a nice size. If > 32K align to 4K boundary else up to max_align_t. The > 32K
     // heuristic is from the JEMalloc behavior.
     {
         uint32_t mask = allocationSize > (1 << 15) ? (1 << 12) - 1 : 16 - 1;
+        SkASSERT_RELEASE(allocationSize <= maxSize - mask);
         allocationSize = (allocationSize + mask) & ~mask;
     }
 

gfx/skia/skia/src/core/SkArenaAlloc.h

@@ -157,6 +157,7 @@ private:
     template <typename T>
     char* commonArrayAlloc(uint32_t count) {
         char* objStart;
+        SkASSERT_RELEASE(count <= std::numeric_limits<uint32_t>::max() / sizeof(T));
         uint32_t arraySize = SkTo<uint32_t>(count * sizeof(T));
         uint32_t alignment = SkTo<uint32_t>(alignof(T));
 
@@ -164,7 +165,9 @@ private:
             objStart = this->allocObject(arraySize, alignment);
             fCursor = objStart + arraySize;
         } else {
-            uint32_t totalSize = arraySize + sizeof(Footer) + sizeof(uint32_t);
+            constexpr uint32_t overhead = sizeof(Footer) + sizeof(uint32_t);
+            SkASSERT_RELEASE(arraySize <= std::numeric_limits<uint32_t>::max() - overhead);
+            uint32_t totalSize = arraySize + overhead;
             objStart = this->allocObjectWithFooter(totalSize, alignment);
 
             // Can never be UB because max value is alignof(T).