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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/200025">200025</a></dd>
<dt>Author</dt> <dd>carlosgc@webkit.org</dd>
<dt>Date</dt> <dd>2016-04-25 08:53:24 -0700 (Mon, 25 Apr 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/199759">r199759</a> - bmalloc: fix up overflow checks
https://bugs.webkit.org/show_bug.cgi?id=156780
Reviewed by Mark Lam.
We used to try to avoid overflow in large object math by setting a very
high limit on the largest large object. But that's a bit error-prone
since the check is far away from the math that might overflow -- and
we were missing some cases.
This patch removes the limit and instead checks at each math site.
* bmalloc/Allocator.cpp:
(bmalloc::Allocator::tryAllocate):
(bmalloc::Allocator::allocate):
(bmalloc::Allocator::reallocate):
(bmalloc::Allocator::allocateSlowCase): Remove the limit. tryAllocateLarge
will check for overflow for us.
* bmalloc/Chunk.h: This ASSERT was just totally wrong.
* bmalloc/Heap.cpp:
(bmalloc::Heap::tryAllocateLarge): Check for overflow when adding.
* bmalloc/Sizes.h:
* bmalloc/VMAllocate.h:
(bmalloc::tryVMAllocate): Check for overflow when adding.
* bmalloc/VMHeap.cpp:
(bmalloc::VMHeap::tryAllocateLargeChunk): Check for overflow when adding.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocChangeLog">releases/WebKitGTK/webkit-2.12/Source/bmalloc/ChangeLog</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocAllocatorcpp">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Allocator.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocChunkh">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Chunk.h</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocHeapcpp">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Heap.cpp</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocSizesh">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Sizes.h</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocVMAllocateh">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMAllocate.h</a></li>
<li><a href="#releasesWebKitGTKwebkit212SourcebmallocbmallocVMHeapcpp">releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMHeap.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="releasesWebKitGTKwebkit212SourcebmallocChangeLog"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/ChangeLog (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/ChangeLog 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/ChangeLog 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -1,5 +1,39 @@
</span><span class="cx"> 2016-04-19 Geoffrey Garen <ggaren@apple.com>
</span><span class="cx">
</span><ins>+ bmalloc: fix up overflow checks
+ https://bugs.webkit.org/show_bug.cgi?id=156780
+
+ Reviewed by Mark Lam.
+
+ We used to try to avoid overflow in large object math by setting a very
+ high limit on the largest large object. But that's a bit error-prone
+ since the check is far away from the math that might overflow -- and
+ we were missing some cases.
+
+ This patch removes the limit and instead checks at each math site.
+
+ * bmalloc/Allocator.cpp:
+ (bmalloc::Allocator::tryAllocate):
+ (bmalloc::Allocator::allocate):
+ (bmalloc::Allocator::reallocate):
+ (bmalloc::Allocator::allocateSlowCase): Remove the limit. tryAllocateLarge
+ will check for overflow for us.
+
+ * bmalloc/Chunk.h: This ASSERT was just totally wrong.
+
+ * bmalloc/Heap.cpp:
+ (bmalloc::Heap::tryAllocateLarge): Check for overflow when adding.
+
+ * bmalloc/Sizes.h:
+
+ * bmalloc/VMAllocate.h:
+ (bmalloc::tryVMAllocate): Check for overflow when adding.
+
+ * bmalloc/VMHeap.cpp:
+ (bmalloc::VMHeap::tryAllocateLargeChunk): Check for overflow when adding.
+
+2016-04-19 Geoffrey Garen <ggaren@apple.com>
+
</ins><span class="cx"> Unreviewed, try to fix an ASSERT seen on the bots.
</span><span class="cx">
</span><span class="cx"> * bmalloc/Heap.cpp:
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocAllocatorcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Allocator.cpp (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Allocator.cpp 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Allocator.cpp 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -58,12 +58,8 @@
</span><span class="cx"> if (size <= smallMax)
</span><span class="cx"> return allocate(size);
</span><span class="cx">
</span><del>- if (size <= largeMax) {
- std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
- return PerProcess<Heap>::getFastCase()->tryAllocateLarge(lock, alignment, size);
- }
-
- return nullptr;
</del><ins>+ std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
+ return PerProcess<Heap>::getFastCase()->tryAllocateLarge(lock, alignment, size);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void* Allocator::allocate(size_t alignment, size_t size)
</span><span class="lines">@@ -83,13 +79,8 @@
</span><span class="cx"> if (size <= smallMax && alignment <= smallMax)
</span><span class="cx"> return allocate(roundUpToMultipleOf(alignment, size));
</span><span class="cx">
</span><del>- if (size <= largeMax && alignment <= largeMax / 2) {
- std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
- return PerProcess<Heap>::getFastCase()->allocateLarge(lock, alignment, size);
- }
-
- BCRASH();
- return nullptr;
</del><ins>+ std::lock_guard<StaticMutex> lock(PerProcess<Heap>::mutex());
+ return PerProcess<Heap>::getFastCase()->allocateLarge(lock, alignment, size);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void* Allocator::reallocate(void* object, size_t newSize)
</span><span class="lines">@@ -193,11 +184,7 @@
</span><span class="cx"> if (size <= smallMax)
</span><span class="cx"> return allocateLogSizeClass(size);
</span><span class="cx">
</span><del>- if (size <= largeMax)
- return allocateLarge(size);
-
- BCRASH();
- return nullptr;
</del><ins>+ return allocateLarge(size);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> } // namespace bmalloc
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocChunkh"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Chunk.h (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Chunk.h 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Chunk.h 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -56,8 +56,6 @@
</span><span class="cx"> std::array<SmallPage, chunkSize / smallPageSize> m_pages;
</span><span class="cx"> };
</span><span class="cx">
</span><del>-static_assert(sizeof(Chunk) + largeMax <= chunkSize, "largeMax is too big");
-
</del><span class="cx"> struct ChunkHash {
</span><span class="cx"> static unsigned hash(Chunk* key)
</span><span class="cx"> {
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocHeapcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Heap.cpp (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Heap.cpp 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Heap.cpp 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -342,13 +342,18 @@
</span><span class="cx">
</span><span class="cx"> void* Heap::tryAllocateLarge(std::lock_guard<StaticMutex>& lock, size_t alignment, size_t size)
</span><span class="cx"> {
</span><del>- BASSERT(size <= largeMax);
- BASSERT(alignment <= largeMax / 2);
</del><span class="cx"> BASSERT(isPowerOfTwo(alignment));
</span><span class="cx">
</span><del>- size = size ? roundUpToMultipleOf(largeAlignment, size) : largeAlignment;
- alignment = roundUpToMultipleOf<largeAlignment>(alignment);
</del><ins>+ size_t roundedSize = size ? roundUpToMultipleOf(largeAlignment, size) : largeAlignment;
+ if (roundedSize < size) // Check for overflow
+ return nullptr;
+ size = roundedSize;
</ins><span class="cx">
</span><ins>+ size_t roundedAlignment = roundUpToMultipleOf<largeAlignment>(alignment);
+ if (roundedAlignment < alignment) // Check for overflow
+ return nullptr;
+ alignment = roundedAlignment;
+
</ins><span class="cx"> XLargeRange range = m_largeFree.remove(alignment, size);
</span><span class="cx"> if (!range) {
</span><span class="cx"> range = m_vmHeap.tryAllocateLargeChunk(lock, alignment, size);
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocSizesh"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Sizes.h (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Sizes.h 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/Sizes.h 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -64,7 +64,6 @@
</span><span class="cx">
</span><span class="cx"> static const size_t largeAlignment = smallMax / pageSizeWasteFactor;
</span><span class="cx"> static const size_t largeAlignmentMask = largeAlignment - 1;
</span><del>- static const size_t largeMax = std::numeric_limits<size_t>::max() - largeAlignment; // Make sure that rounding up to largeAlignment does not overflow.
</del><span class="cx">
</span><span class="cx"> static const size_t deallocatorLogCapacity = 256;
</span><span class="cx"> static const size_t bumpRangeCacheCapacity = 3;
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocVMAllocateh"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMAllocate.h (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMAllocate.h 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMAllocate.h 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -145,7 +145,10 @@
</span><span class="cx"> vmValidate(vmSize);
</span><span class="cx"> vmValidate(vmAlignment);
</span><span class="cx">
</span><del>- size_t mappedSize = vmAlignment - vmPageSize() + vmSize;
</del><ins>+ size_t mappedSize = vmAlignment + vmSize;
+ if (mappedSize < vmAlignment || mappedSize < vmSize) // Check for overflow
+ return nullptr;
+
</ins><span class="cx"> char* mapped = static_cast<char*>(tryVMAllocate(mappedSize));
</span><span class="cx"> if (!mapped)
</span><span class="cx"> return nullptr;
</span></span></pre></div>
<a id="releasesWebKitGTKwebkit212SourcebmallocbmallocVMHeapcpp"></a>
<div class="modfile"><h4>Modified: releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMHeap.cpp (200024 => 200025)</h4>
<pre class="diff"><span>
<span class="info">--- releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMHeap.cpp 2016-04-25 15:53:03 UTC (rev 200024)
+++ releases/WebKitGTK/webkit-2.12/Source/bmalloc/bmalloc/VMHeap.cpp 2016-04-25 15:53:24 UTC (rev 200025)
</span><span class="lines">@@ -33,9 +33,16 @@
</span><span class="cx"> {
</span><span class="cx"> // We allocate VM in aligned multiples to increase the chances that
</span><span class="cx"> // the OS will provide contiguous ranges that we can merge.
</span><del>- alignment = roundUpToMultipleOf<chunkSize>(alignment);
- size = roundUpToMultipleOf<chunkSize>(size);
</del><ins>+ size_t roundedAlignment = roundUpToMultipleOf<chunkSize>(alignment);
+ if (roundedAlignment < alignment) // Check for overflow
+ return XLargeRange();
+ alignment = roundedAlignment;
</ins><span class="cx">
</span><ins>+ size_t roundedSize = roundUpToMultipleOf<chunkSize>(size);
+ if (roundedSize < size) // Check for overflow
+ return XLargeRange();
+ size = roundedSize;
+
</ins><span class="cx"> void* memory = tryVMAllocate(alignment, size);
</span><span class="cx"> if (!memory)
</span><span class="cx"> return XLargeRange();
</span></span></pre>
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