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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/202173">202173</a></dd>
<dt>Author</dt> <dd>mark.lam@apple.com</dd>
<dt>Date</dt> <dd>2016-06-17 12:22:02 -0700 (Fri, 17 Jun 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>OOM Assertion failure in JSON.stringify.
https://bugs.webkit.org/show_bug.cgi?id=158794
<rdar://problem/26826254>
Reviewed by Saam Barati.
The bug was actually in StringBuilder::appendQuotedJSONString() where it failed
to detect an imminent unsigned int overflow. The fix is to use Checked<unsigned>
for the needed math, and RELEASE_ASSERT afterwards that we did not overflow.
I also added more assertions to detect sooner if any there are any problems with
StringBuilder's m_buffer or m_length being incorrectly sized. These assertions
have been run on the JSC and layout tests without any issue.
* wtf/text/StringBuilder.cpp:
(WTF::StringBuilder::resize):
(WTF::StringBuilder::allocateBuffer):
(WTF::StringBuilder::allocateBufferUpConvert):
(WTF::StringBuilder::reallocateBuffer<LChar>):
(WTF::StringBuilder::reallocateBuffer<UChar>):
(WTF::StringBuilder::reserveCapacity):
(WTF::StringBuilder::appendUninitializedSlow):
(WTF::StringBuilder::append):
(WTF::StringBuilder::appendQuotedJSONString):
* wtf/text/StringBuilder.h:
(WTF::StringBuilder::swap):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWTFChangeLog">trunk/Source/WTF/ChangeLog</a></li>
<li><a href="#trunkSourceWTFwtftextStringBuildercpp">trunk/Source/WTF/wtf/text/StringBuilder.cpp</a></li>
<li><a href="#trunkSourceWTFwtftextStringBuilderh">trunk/Source/WTF/wtf/text/StringBuilder.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWTFChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WTF/ChangeLog (202172 => 202173)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WTF/ChangeLog 2016-06-17 19:10:28 UTC (rev 202172)
+++ trunk/Source/WTF/ChangeLog 2016-06-17 19:22:02 UTC (rev 202173)
</span><span class="lines">@@ -1,3 +1,32 @@
</span><ins>+2016-06-17 Mark Lam <mark.lam@apple.com>
+
+ OOM Assertion failure in JSON.stringify.
+ https://bugs.webkit.org/show_bug.cgi?id=158794
+ <rdar://problem/26826254>
+
+ Reviewed by Saam Barati.
+
+ The bug was actually in StringBuilder::appendQuotedJSONString() where it failed
+ to detect an imminent unsigned int overflow. The fix is to use Checked<unsigned>
+ for the needed math, and RELEASE_ASSERT afterwards that we did not overflow.
+
+ I also added more assertions to detect sooner if any there are any problems with
+ StringBuilder's m_buffer or m_length being incorrectly sized. These assertions
+ have been run on the JSC and layout tests without any issue.
+
+ * wtf/text/StringBuilder.cpp:
+ (WTF::StringBuilder::resize):
+ (WTF::StringBuilder::allocateBuffer):
+ (WTF::StringBuilder::allocateBufferUpConvert):
+ (WTF::StringBuilder::reallocateBuffer<LChar>):
+ (WTF::StringBuilder::reallocateBuffer<UChar>):
+ (WTF::StringBuilder::reserveCapacity):
+ (WTF::StringBuilder::appendUninitializedSlow):
+ (WTF::StringBuilder::append):
+ (WTF::StringBuilder::appendQuotedJSONString):
+ * wtf/text/StringBuilder.h:
+ (WTF::StringBuilder::swap):
+
</ins><span class="cx"> 2016-06-14 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><span class="cx"> Baseline JIT should be concurrent
</span></span></pre></div>
<a id="trunkSourceWTFwtftextStringBuildercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WTF/wtf/text/StringBuilder.cpp (202172 => 202173)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WTF/wtf/text/StringBuilder.cpp 2016-06-17 19:10:28 UTC (rev 202172)
+++ trunk/Source/WTF/wtf/text/StringBuilder.cpp 2016-06-17 19:22:02 UTC (rev 202173)
</span><span class="lines">@@ -1,5 +1,5 @@
</span><span class="cx"> /*
</span><del>- * Copyright (C) 2010, 2013 Apple Inc. All rights reserved.
</del><ins>+ * Copyright (C) 2010, 2013, 2016 Apple Inc. All rights reserved.
</ins><span class="cx"> * Copyright (C) 2012 Google Inc. All rights reserved.
</span><span class="cx"> *
</span><span class="cx"> * Redistribution and use in source and binary forms, with or without
</span><span class="lines">@@ -80,6 +80,7 @@
</span><span class="cx"> allocateBuffer(m_buffer->characters16(), m_buffer->length());
</span><span class="cx"> }
</span><span class="cx"> m_length = newSize;
</span><ins>+ ASSERT(m_buffer->length() >= m_length);
</ins><span class="cx"> return;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -103,6 +104,7 @@
</span><span class="cx"> // Update the builder state.
</span><span class="cx"> m_buffer = WTFMove(buffer);
</span><span class="cx"> m_string = String();
</span><ins>+ ASSERT(m_buffer->length() == requiredLength);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> // Allocate a new 16 bit buffer, copying in currentCharacters (these may come from either m_string
</span><span class="lines">@@ -117,6 +119,7 @@
</span><span class="cx"> // Update the builder state.
</span><span class="cx"> m_buffer = WTFMove(buffer);
</span><span class="cx"> m_string = String();
</span><ins>+ ASSERT(m_buffer->length() == requiredLength);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> // Allocate a new 16 bit buffer, copying in currentCharacters (which is 8 bit and may come
</span><span class="lines">@@ -124,6 +127,7 @@
</span><span class="cx"> void StringBuilder::allocateBufferUpConvert(const LChar* currentCharacters, unsigned requiredLength)
</span><span class="cx"> {
</span><span class="cx"> ASSERT(m_is8Bit);
</span><ins>+ ASSERT(requiredLength >= m_length);
</ins><span class="cx"> // Copy the existing data into a new buffer, set result to point to the end of the existing data.
</span><span class="cx"> auto buffer = StringImpl::createUninitialized(requiredLength, m_bufferCharacters16);
</span><span class="cx"> for (unsigned i = 0; i < m_length; ++i)
</span><span class="lines">@@ -134,6 +138,7 @@
</span><span class="cx"> // Update the builder state.
</span><span class="cx"> m_buffer = WTFMove(buffer);
</span><span class="cx"> m_string = String();
</span><ins>+ ASSERT(m_buffer->length() == requiredLength);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> template <>
</span><span class="lines">@@ -150,6 +155,7 @@
</span><span class="cx"> m_buffer = StringImpl::reallocate(m_buffer.releaseNonNull(), requiredLength, m_bufferCharacters8);
</span><span class="cx"> else
</span><span class="cx"> allocateBuffer(m_buffer->characters8(), requiredLength);
</span><ins>+ ASSERT(m_buffer->length() == requiredLength);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> template <>
</span><span class="lines">@@ -165,6 +171,7 @@
</span><span class="cx"> m_buffer = StringImpl::reallocate(m_buffer.releaseNonNull(), requiredLength, m_bufferCharacters16);
</span><span class="cx"> else
</span><span class="cx"> allocateBuffer(m_buffer->characters16(), requiredLength);
</span><ins>+ ASSERT(m_buffer->length() == requiredLength);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void StringBuilder::reserveCapacity(unsigned newCapacity)
</span><span class="lines">@@ -189,6 +196,7 @@
</span><span class="cx"> allocateBuffer(m_string.characters16(), newCapacity);
</span><span class="cx"> }
</span><span class="cx"> }
</span><ins>+ ASSERT(!newCapacity || m_buffer->length() >= newCapacity);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> // Make 'length' additional capacity be available in m_buffer, update m_string & m_length,
</span><span class="lines">@@ -234,6 +242,7 @@
</span><span class="cx">
</span><span class="cx"> CharType* result = getBufferCharacters<CharType>() + m_length;
</span><span class="cx"> m_length = requiredLength;
</span><ins>+ ASSERT(m_buffer->length() >= m_length);
</ins><span class="cx"> return result;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -267,10 +276,11 @@
</span><span class="cx"> allocateBufferUpConvert(m_string.isNull() ? 0 : m_string.characters8(), expandedCapacity(capacity(), requiredLength));
</span><span class="cx"> }
</span><span class="cx">
</span><del>- memcpy(m_bufferCharacters16 + m_length, characters, static_cast<size_t>(length) * sizeof(UChar));
</del><ins>+ memcpy(m_bufferCharacters16 + m_length, characters, static_cast<size_t>(length) * sizeof(UChar));
</ins><span class="cx"> m_length = requiredLength;
</span><span class="cx"> } else
</span><span class="cx"> memcpy(appendUninitialized<UChar>(length), characters, static_cast<size_t>(length) * sizeof(UChar));
</span><ins>+ ASSERT(m_buffer->length() >= m_length);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void StringBuilder::append(const LChar* characters, unsigned length)
</span><span class="lines">@@ -412,9 +422,10 @@
</span><span class="cx"> // to worry about reallocating in the middle.
</span><span class="cx"> // The 2 is for the '"' quotes on each end.
</span><span class="cx"> // The 6 is for characters that need to be \uNNNN encoded.
</span><del>- size_t maximumCapacityRequired = length() + 2 + string.length() * 6;
- RELEASE_ASSERT(maximumCapacityRequired < std::numeric_limits<unsigned>::max());
- unsigned allocationSize = maximumCapacityRequired;
</del><ins>+ Checked<unsigned> stringLength = string.length();
+ Checked<unsigned> maximumCapacityRequired = length();
+ maximumCapacityRequired += 2 + stringLength * 6;
+ unsigned allocationSize = maximumCapacityRequired.unsafeGet();
</ins><span class="cx"> // This max() is here to allow us to allocate sizes between the range [2^31, 2^32 - 2] because roundUpToPowerOfTwo(1<<31 + some int smaller than 1<<31) == 0.
</span><span class="cx"> allocationSize = std::max(allocationSize, roundUpToPowerOfTwo(allocationSize));
</span><span class="cx">
</span><span class="lines">@@ -422,6 +433,7 @@
</span><span class="cx"> allocateBufferUpConvert(m_bufferCharacters8, allocationSize);
</span><span class="cx"> else
</span><span class="cx"> reserveCapacity(allocationSize);
</span><ins>+ ASSERT(m_buffer->length() >= allocationSize);
</ins><span class="cx">
</span><span class="cx"> if (is8Bit()) {
</span><span class="cx"> ASSERT(string.is8Bit());
</span><span class="lines">@@ -440,6 +452,7 @@
</span><span class="cx"> *output++ = '"';
</span><span class="cx"> m_length = output - m_bufferCharacters16;
</span><span class="cx"> }
</span><ins>+ ASSERT(m_buffer->length() >= m_length);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> } // namespace WTF
</span></span></pre></div>
<a id="trunkSourceWTFwtftextStringBuilderh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WTF/wtf/text/StringBuilder.h (202172 => 202173)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WTF/wtf/text/StringBuilder.h 2016-06-17 19:10:28 UTC (rev 202172)
+++ trunk/Source/WTF/wtf/text/StringBuilder.h 2016-06-17 19:22:02 UTC (rev 202173)
</span><span class="lines">@@ -1,5 +1,5 @@
</span><span class="cx"> /*
</span><del>- * Copyright (C) 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
</del><ins>+ * Copyright (C) 2009-2010, 2012-2013, 2016 Apple Inc. All rights reserved.
</ins><span class="cx"> * Copyright (C) 2012 Google Inc. All rights reserved.
</span><span class="cx"> *
</span><span class="cx"> * Redistribution and use in source and binary forms, with or without
</span><span class="lines">@@ -276,6 +276,7 @@
</span><span class="cx"> m_buffer.swap(stringBuilder.m_buffer);
</span><span class="cx"> std::swap(m_is8Bit, stringBuilder.m_is8Bit);
</span><span class="cx"> std::swap(m_bufferCharacters8, stringBuilder.m_bufferCharacters8);
</span><ins>+ ASSERT(!m_buffer || m_buffer->length() >= m_length);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> private:
</span></span></pre>
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