From: Pete Cooper <peter_cooper@apple.com>
Date: Wed, 23 Mar 2016 18:00:10 +0000 (+0000)
Subject: Copy MachO struct to temporary to avoid unaligned load UB.
X-Git-Tag: llvmorg-3.9.0-rc1~11145
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e82f3a099fa5c3b81eca29c4d5d0ce9ae4cdd923;p=platform%2Fupstream%2Fllvm.git

Copy MachO struct to temporary to avoid unaligned load UB.

We were already copying this data to a temporary for endian swaps.  Now
we just always copy it, but still only do the endian swaps when needed.

llvm-svn: 264172
---

diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
index 7a9dd4b..39860bb 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryReader.cpp
@@ -380,11 +380,11 @@ readBinary(std::unique_ptr<MemoryBuffer> &mb,
             reinterpret_cast<const nlist_64 *>(start + symOffset);
         // Convert each nlist_64 to a lld::mach_o::normalized::Symbol.
         for(uint32_t i=0; i < symCount; ++i) {
-          const nlist_64 *sin = &symbols[i];
           nlist_64 tempSym;
-          if (isBig != llvm::sys::IsBigEndianHost) {
-            tempSym = *sin; swapStruct(tempSym); sin = &tempSym;
-          }
+          memcpy(&tempSym, &symbols[i], sizeof(nlist_64));
+          const nlist_64 *sin = &tempSym;
+          if (isBig != llvm::sys::IsBigEndianHost)
+            swapStruct(tempSym);
           Symbol sout;
           if (sin->n_strx > strSize)
             return true;