[llvm] r206146 - tools: simplify symbol handling in objdump

[Evgeniy Stepanov]

Hi,

something in this change caused a heap buffer overflow:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/3022/steps/check-llvm%20asan/logs/stdio


On Mon, Apr 14, 2014 at 6:37 AM, Saleem Abdulrasool
<compnerd at compnerd.org> wrote:
> Author: compnerd
> Date: Sun Apr 13 21:37:28 2014
> New Revision: 206146
>
> URL: http://llvm.org/viewvc/llvm-project?rev=206146&view=rev
> Log:
> tools: simplify symbol handling in objdump
>
> Rather than switching behaviour on whether a previous symbol has an auxiliary
> symbol record for the next count of elements, simply iterate over the auxiliary
> symbols right after processing the current symbol entry.  This makes the
> behaviour much simpler to follow and similar to llvm-readobj and yaml2obj.
>
> Modified:
>     llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp
>
> Modified: llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp?rev=206146&r1=206145&r2=206146&view=diff
> ==============================================================================
> --- llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp (original)
> +++ llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp Sun Apr 13 21:37:28 2014
> @@ -664,14 +664,31 @@ static void PrintSectionContents(const O
>
>  static void PrintCOFFSymbolTable(const COFFObjectFile *coff) {
>    const coff_file_header *header;
> -  if (error(coff->getHeader(header))) return;
> -  int aux_count = 0;
> -  const coff_symbol *symbol = 0;
> -  for (int i = 0, e = header->NumberOfSymbols; i != e; ++i) {
> -    if (aux_count--) {
> -      if (symbol->isSectionDefinition()) {
> +  if (error(coff->getHeader(header)))
> +    return;
> +
> +  for (unsigned SI = 0, SE = header->NumberOfSymbols; SI != SE; ++SI) {
> +    const coff_symbol *Symbol;
> +    StringRef Name;
> +    if (error(coff->getSymbol(SI, Symbol)))
> +      return;
> +
> +    if (error(coff->getSymbolName(Symbol, Name)))
> +      return;
> +
> +    outs() << "[" << format("%2d", SI) << "]"
> +           << "(sec " << format("%2d", int(Symbol->SectionNumber)) << ")"
> +           << "(fl 0x00)" // Flag bits, which COFF doesn't have.
> +           << "(ty " << format("%3x", unsigned(Symbol->Type)) << ")"
> +           << "(scl " << format("%3x", unsigned(Symbol->StorageClass)) << ") "
> +           << "(nx " << unsigned(Symbol->NumberOfAuxSymbols) << ") "
> +           << "0x" << format("%08x", unsigned(Symbol->Value)) << " "
> +           << Name << "\n";
> +
> +    for (unsigned AI = 0, AE = Symbol->NumberOfAuxSymbols; AI < AE; ++AI, ++SI) {
> +      if (Symbol->isSectionDefinition()) {
>          const coff_aux_section_definition *asd;
> -        if (error(coff->getAuxSymbol<coff_aux_section_definition>(i, asd)))
> +        if (error(coff->getAuxSymbol<coff_aux_section_definition>(SI + 1, asd)))
>            return;
>
>          outs() << "AUX "
> @@ -683,31 +700,17 @@ static void PrintCOFFSymbolTable(const C
>                 << format("assoc %d comdat %d\n"
>                           , unsigned(asd->Number)
>                           , unsigned(asd->Selection));
> -      } else if (symbol->isFileRecord()) {
> +      } else if (Symbol->isFileRecord()) {
>          const coff_aux_file *AF;
> -        if (error(coff->getAuxSymbol<coff_aux_file>(i, AF)))
> +        if (error(coff->getAuxSymbol<coff_aux_file>(SI + 1, AF)))
>            return;
>
> -        StringRef Name(AF->FileName, (aux_count + 1) * COFF::SymbolSize);
> +        StringRef Name(AF->FileName,
> +                       Symbol->NumberOfAuxSymbols * COFF::SymbolSize);
>          outs() << "AUX " << Name.rtrim(StringRef("\0", 1))  << '\n';
> -        i = i + aux_count;
> -        aux_count = 0;
>        } else {
>          outs() << "AUX Unknown\n";
>        }
> -    } else {
> -      StringRef name;
> -      if (error(coff->getSymbol(i, symbol))) return;
> -      if (error(coff->getSymbolName(symbol, name))) return;
> -      outs() << "[" << format("%2d", i) << "]"
> -             << "(sec " << format("%2d", int(symbol->SectionNumber)) << ")"
> -             << "(fl 0x00)" // Flag bits, which COFF doesn't have.
> -             << "(ty " << format("%3x", unsigned(symbol->Type)) << ")"
> -             << "(scl " << format("%3x", unsigned(symbol->StorageClass)) << ") "
> -             << "(nx " << unsigned(symbol->NumberOfAuxSymbols) << ") "
> -             << "0x" << format("%08x", unsigned(symbol->Value)) << " "
> -             << name << "\n";
> -      aux_count = symbol->NumberOfAuxSymbols;
>      }
>    }
>  }
>
>
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