[llvm] [MachO] Fix unaligned load in extractSections (PR #68741)

[Thurston Dang via llvm-commits]

https://github.com/thurstond created https://github.com/llvm/llvm-project/pull/68741

A recent change to ubsan
(https://github.com/llvm/llvm-project/commit/792674400f6f04a074a3827349ed0e2ac10067f6)
exposed an unaligned load in MachOReader (see
https://lab.llvm.org/buildbot/#/builders/85/builds/19482 for an example).

This patch fixes it by dropping the alignment.


>From b37687344d667b0ac71f7d80e19c48e0629fc221 Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Tue, 10 Oct 2023 20:08:04 +0000
Subject: [PATCH] [MachO] Fix unaligned load in extractSections

A recent change to ubsan
(https://github.com/llvm/llvm-project/commit/792674400f6f04a074a3827349ed0e2ac10067f6)
exposed an unaligned load in MachOReader (see
https://lab.llvm.org/buildbot/#/builders/85/builds/19482 for an example).

This patch fixes it by dropping the alignment.
---
 llvm/lib/ObjCopy/MachO/MachOReader.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/ObjCopy/MachO/MachOReader.cpp b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
index 2cbffc12adbf765..9006f9e6d98d951 100644
--- a/llvm/lib/ObjCopy/MachO/MachOReader.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
@@ -67,7 +67,7 @@ Expected<std::vector<std::unique_ptr<Section>>> static extractSections(
                                                         LoadCmd.C.cmdsize);
        Curr < End; ++Curr) {
     SectionType Sec;
-    memcpy((void *)&Sec, Curr, sizeof(SectionType));
+    memcpy((void *)&Sec, reinterpret_cast<const char*>(Curr), sizeof(SectionType));
 
     if (MachOObj.isLittleEndian() != sys::IsLittleEndianHost)
       MachO::swapStruct(Sec);