[PATCH] D139315: [NFC][LLVM-MT] Fix buffer-overflow when comparing buffers

[Juan Manuel Martinez Caamaño via Phabricator via llvm-commits]

jmmartinez updated this revision to Diff 480402.
jmmartinez added a comment.

In fact, bring back the size comparison to speed up the comparison in the case the sizes do not match


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139315/new/

https://reviews.llvm.org/D139315

Files:
  llvm/tools/llvm-mt/llvm-mt.cpp


Index: llvm/tools/llvm-mt/llvm-mt.cpp
===================================================================
--- llvm/tools/llvm-mt/llvm-mt.cpp
+++ llvm/tools/llvm-mt/llvm-mt.cpp
@@ -150,9 +150,12 @@
     bool Same = false;
     if (OutBuffOrErr) {
       const std::unique_ptr<MemoryBuffer> &FileBuffer = *OutBuffOrErr;
-      Same = std::equal(OutputBuffer->getBufferStart(),
-                        OutputBuffer->getBufferEnd(),
-                        FileBuffer->getBufferStart());
+      bool SameSize =
+          OutputBuffer->getBufferSize() == FileBuffer->getBufferSize();
+      Same = SameSize && std::equal(OutputBuffer->getBufferStart(),
+                                    OutputBuffer->getBufferEnd(),
+                                    FileBuffer->getBufferStart(),
+                                    FileBuffer->getBufferEnd());
     }
     if (!Same) {
 #if LLVM_ON_UNIX


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