From 0da1540aaa8d36145329572938aeec6c86fb1ee7 Mon Sep 17 00:00:00 2001
From: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>
Date: Thu, 17 Jun 2021 13:18:13 +0100
Subject: cmELF: Fix check for TagMipsRldMapRel

DT_MIPS_RLD_MAP_REL is a machine-speicific dynamic tag, so other
architectures could re-use the value of 0x70000035 to mean something
else.  Before using DT_MIPS_RLD_MAP_REL, we have to check that the ELF
file is actually has a e_machine of EM_MIPS.
---
 Source/cmELF.cxx         | 15 +++++++++++++++
 Source/cmELF.h           |  3 +++
 Source/cmSystemTools.cxx |  3 +--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Source/cmELF.cxx b/Source/cmELF.cxx
index 01dc0b1..d96644b 100644
--- a/Source/cmELF.cxx
+++ b/Source/cmELF.cxx
@@ -145,6 +145,7 @@ public:
   virtual std::vector<char> EncodeDynamicEntries(
     const cmELF::DynamicEntryList&) = 0;
   virtual StringEntry const* GetDynamicSectionString(unsigned int tag) = 0;
+  virtual bool IsMips() const = 0;
   virtual void PrintInfo(std::ostream& os) const = 0;
 
   // Lookup the SONAME in the DYNAMIC section.
@@ -256,6 +257,12 @@ public:
   // Lookup a string from the dynamic section with the given tag.
   StringEntry const* GetDynamicSectionString(unsigned int tag) override;
 
+#ifdef EM_MIPS
+  bool IsMips() const override { return this->ELFHeader.e_machine == EM_MIPS; }
+#else
+  bool IsMips() const override { false; }
+#endif
+
   // Print information about the ELF file.
   void PrintInfo(std::ostream& os) const override
   {
@@ -830,6 +837,14 @@ cmELF::StringEntry const* cmELF::GetRunPath()
   return nullptr;
 }
 
+bool cmELF::IsMIPS() const
+{
+  if (this->Valid()) {
+    return this->Internal->IsMips();
+  }
+  return false;
+}
+
 void cmELF::PrintInfo(std::ostream& os) const
 {
   if (this->Valid()) {
diff --git a/Source/cmELF.h b/Source/cmELF.h
index c479e2b..5700a38 100644
--- a/Source/cmELF.h
+++ b/Source/cmELF.h
@@ -98,6 +98,9 @@ public:
   /** Get the RUNPATH field if any.  */
   StringEntry const* GetRunPath();
 
+  /** Returns true if the ELF file targets a MIPS CPU.  */
+  bool IsMIPS() const;
+
   /** Print human-readable information about the ELF file.  */
   void PrintInfo(std::ostream& os) const;
 
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 488e69c..d6b8208 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -3102,8 +3102,7 @@ static cm::optional<bool> RemoveRPathELF(std::string const& file,
         entriesErased++;
         continue;
       }
-      if (cmELF::TagMipsRldMapRel != 0 &&
-          it->first == cmELF::TagMipsRldMapRel) {
+      if (it->first == cmELF::TagMipsRldMapRel && elf.IsMIPS()) {
         // Background: debuggers need to know the "linker map" which contains
         // the addresses each dynamic object is loaded at. Most arches use
         // the DT_DEBUG tag which the dynamic linker writes to (directly) and
-- 
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