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Object: avoid undefined behavior when bounds-checking
Don't form an out of bounds pointer just to test if it would be out of bounds. Also perform the same bounds checking for all the previous mapped structures. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149750 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1173,25 +1173,36 @@ ELFObjectFile<target_endianness, is64Bits>::ELFObjectFile(MemoryBuffer *Object
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, SectionHeaderTable(0)
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, dot_shstrtab_sec(0)
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, dot_strtab_sec(0) {
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const uint64_t FileSize = Data->getBufferSize();
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if (sizeof(Elf_Ehdr) > FileSize)
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// FIXME: Proper error handling.
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report_fatal_error("File too short!");
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Header = reinterpret_cast<const Elf_Ehdr *>(base());
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if (Header->e_shoff == 0)
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return;
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SectionHeaderTable =
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reinterpret_cast<const Elf_Shdr *>(base() + Header->e_shoff);
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uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
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const uint64_t SectionTableOffset = Header->e_shoff;
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if ((const uint8_t *)SectionHeaderTable + SectionTableSize
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> base() + Data->getBufferSize()) {
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if (SectionTableOffset + sizeof(Elf_Shdr) > FileSize)
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// FIXME: Proper error handling.
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report_fatal_error("Section header table goes past end of file!");
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// The getNumSections() call below depends on SectionHeaderTable being set.
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SectionHeaderTable =
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reinterpret_cast<const Elf_Shdr *>(base() + SectionTableOffset);
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const uint64_t SectionTableSize = getNumSections() * Header->e_shentsize;
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if (SectionTableOffset + SectionTableSize > FileSize)
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// FIXME: Proper error handling.
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report_fatal_error("Section table goes past end of file!");
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}
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// To find the symbol tables we walk the section table to find SHT_SYMTAB.
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const Elf_Shdr* SymbolTableSectionHeaderIndex = 0;
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const Elf_Shdr* sh = reinterpret_cast<const Elf_Shdr*>(SectionHeaderTable);
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const Elf_Shdr* sh = SectionHeaderTable;
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for (uint64_t i = 0, e = getNumSections(); i != e; ++i) {
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if (sh->sh_type == ELF::SHT_SYMTAB_SHNDX) {
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if (SymbolTableSectionHeaderIndex)
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@ -1357,8 +1368,11 @@ unsigned ELFObjectFile<target_endianness, is64Bits>::getArch() const {
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template<support::endianness target_endianness, bool is64Bits>
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uint64_t ELFObjectFile<target_endianness, is64Bits>::getNumSections() const {
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if (Header->e_shnum == ELF::SHN_UNDEF)
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assert(Header && "Header not initialized!");
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if (Header->e_shnum == ELF::SHN_UNDEF) {
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assert(SectionHeaderTable && "SectionHeaderTable not initialized!");
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return SectionHeaderTable->sh_size;
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}
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return Header->e_shnum;
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}
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