[Courgette] Sort section headers by sh_offset in ELF flows.

courgette/disassembler_elf_32.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "courgette/disassembler_elf_32.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "courgette/assembly_program.h"
 #include "courgette/courgette.h"
 
 namespace courgette {
 
+namespace {
+
+// Initializes |section_header_table| by copying |section_header_table_size|
+// entries from |section_header_table_raw|, and sorting by |sh_offset|.
+void SortSectionHeader(const Elf32_Shdr* section_header_table_raw,
+                       Elf32_Half section_header_table_size,
+                       std::vector<Elf32_Shdr>* section_header_table) {
+  section_header_table->assign(section_header_table_raw,
+      section_header_table_raw + section_header_table_size);
+  auto comp = [](const Elf32_Shdr& header1, const Elf32_Shdr& header2) {
+    return header1.sh_offset < header2.sh_offset;
+  };
+  std::stable_sort(
+      section_header_table->begin(), section_header_table->end(), comp);
+}
+
+}  // namespace
+
 DisassemblerElf32::DisassemblerElf32(const void* start, size_t length)
     : Disassembler(start, length),
       header_(nullptr),
-      section_header_table_(nullptr),
       section_header_table_size_(0),
       program_header_table_(nullptr),
       program_header_table_size_(0),
       default_string_section_(nullptr) {
 }
 
 RVA DisassemblerElf32::FileOffsetToRVA(FileOffset offset) const {
   // File offsets can be 64-bit values, but we are dealing with 32-bit
   // executables and so only need to support 32-bit file sizes.
   uint32_t offset32 = static_cast<uint32_t>(offset);
@@ skipping 59 matching lines @@
 
   if (header_->e_version != 1)
     return Bad("Unknown file version");
 
   if (header_->e_shentsize != sizeof(Elf32_Shdr))
     return Bad("Unexpected section header size");
 
   if (!IsArrayInBounds(header_->e_shoff, header_->e_shnum, sizeof(Elf32_Shdr)))
     return Bad("Out of bounds section header table");
 
-  section_header_table_ = reinterpret_cast<const Elf32_Shdr*>(
-      FileOffsetToPointer(header_->e_shoff));
+  const Elf32_Shdr* section_header_table_raw =
+      reinterpret_cast<const Elf32_Shdr*>(
+          FileOffsetToPointer(header_->e_shoff));
   section_header_table_size_ = header_->e_shnum;
+  SortSectionHeader(section_header_table_raw, section_header_table_size_,
+                    &section_header_table_);
 
   if (!IsArrayInBounds(header_->e_phoff, header_->e_phnum, sizeof(Elf32_Phdr)))
     return Bad("Out of bounds program header table");
 
   program_header_table_ = reinterpret_cast<const Elf32_Phdr*>(
       FileOffsetToPointer(header_->e_phoff));
   program_header_table_size_ = header_->e_phnum;
 
   if (header_->e_shstrndx >= header_->e_shnum)
     return Bad("Out of bounds string section index");
@@ skipping 368 matching lines @@
 
   std::sort(rel32_locations_.begin(),
             rel32_locations_.end(),
             TypedRVA::IsLessThan);
   DCHECK(rel32_locations_.empty() ||
          rel32_locations_.back()->rva() != kUnassignedRVA);
   return true;
 }
 
 }  // namespace courgette