From 4d60f67763b08c19335b29e96a61ad4cbce034d9 Mon Sep 17 00:00:00 2001
From: Xinliang David Li <davidxl@google.com>
Date: Tue, 17 Nov 2015 03:47:21 +0000
Subject: [PATCH] Fix unaligned memory read issue exposed by ubsan

Indexed profile data as designed today does not guarantee
counter data to be well aligned, so reading needs to use
the slower form (with memcpy). This is less than ideal and
should be improved in the future (i.e., with fixed length
function key instead of variable length name key).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253309 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/ProfileData/InstrProf.cpp | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/ProfileData/InstrProf.cpp b/lib/ProfileData/InstrProf.cpp
index 762f00b48b6..ef7b19b2882 100644
--- a/lib/ProfileData/InstrProf.cpp
+++ b/lib/ProfileData/InstrProf.cpp
@@ -184,11 +184,13 @@ void ValueProfRecord::serializeFrom(const InstrProfRecord &Record,
   }
 }
 
-template <class T> static T swapToHostOrder(T v, support::endianness Orig) {
-  if (Orig == getHostEndianness())
-    return v;
-  sys::swapByteOrder<T>(v);
-  return v;
+template <class T>
+static T swapToHostOrder(const unsigned char *&D, support::endianness Orig) {
+  using namespace support;
+  if (Orig == little)
+    return endian::readNext<T, little, unaligned>(D);
+  else
+    return endian::readNext<T, big, unaligned>(D);
 }
 
 // For writing/serializing,  Old is the host endianness, and  New is
@@ -278,10 +280,9 @@ ValueProfData::getValueProfData(const unsigned char *D,
   if (D + sizeof(ValueProfData) > BufferEnd)
     return instrprof_error::truncated;
 
-  uint32_t TotalSize = swapToHostOrder<uint32_t>(
-      reinterpret_cast<const uint32_t *>(D)[0], Endianness);
-  uint32_t NumValueKinds = swapToHostOrder<uint32_t>(
-      reinterpret_cast<const uint32_t *>(D)[1], Endianness);
+  const unsigned char *Header = D;
+  uint32_t TotalSize = swapToHostOrder<uint32_t>(Header, Endianness);
+  uint32_t NumValueKinds = swapToHostOrder<uint32_t>(Header, Endianness);
 
   if (D + TotalSize > BufferEnd)
     return instrprof_error::too_large;
@@ -307,7 +308,6 @@ ValueProfData::getValueProfData(const unsigned char *D,
       return instrprof_error::malformed;
   }
 
-  D += TotalSize;
   return std::move(VPD);
 }
 
-- 
2.34.1