[llvm] ebee5e0 - [Object] Always initialized StartOfFile in Archive::Child::Child constructor.

[Thurston Dang via llvm-commits]

Author: Jacek Caban
Date: 2023-04-22T00:04:30Z
New Revision: ebee5e0473df7685086eb2f4ffb07e1bf965b3bd

URL: https://github.com/llvm/llvm-project/commit/ebee5e0473df7685086eb2f4ffb07e1bf965b3bd
DIFF: https://github.com/llvm/llvm-project/commit/ebee5e0473df7685086eb2f4ffb07e1bf965b3bd.diff

LOG: [Object] Always initialized StartOfFile in Archive::Child::Child constructor.

Fixes uninitialized memory access revealed by https://reviews.llvm.org/D146534.

In empty archives, we use Child(nullptr,nullptr,nullptr) in Archive constructor in setFirstRegular. This copies unitialized StartOfFile to FirstRegularStartOfFile, which child_begin may use later.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D148955

Added: 
    

Modified: 
    llvm/lib/Object/Archive.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 6ddbe3518d8e9..081ff79ff550c 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -468,6 +468,7 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
     : Parent(Parent) {
   if (!Start) {
     Header = nullptr;
+    StartOfFile = -1;
     return;
   }