PE/COFF: raise normal PE section limit safely
Safely increases the maximum number of sections allowed in PE/COFF files processed by binutils.
This patch addresses a limitation in binutils’ handling of PE/COFF files, where symbol section numbers were treated as signed 16-bit integers, restricting normal PE objects to 32,767 sections. The change raises this limit to 65,279 by correctly decoding and encoding section numbers as unsigned values, while preserving special reserved values. It also improves error handling by rejecting invalid reserved section numbers during symbol reading and includes new gas and binutils tests to verify the changes.
- proposer
Proposes a change to safely increase the PE/COFF section limit by properly handling unsigned 16-bit section numbers and adding related tests.
“PE/COFF stores symbol section numbers in a 16-bit field. Binutils used signed 16-bit handling there, which limited normal PE objects to 32767 sections even though MSVC and Clang already accept a larger unsigned range. Raise the normal PE section limit to 65279, while keeping the PE/COFF special section-number values for undefined, absolute and debug symbols working correctly. Do this by decodi…”
In Details
This patch raises the limit for the number of sections supported in PE/COFF files within binutils from 32,767 to 65,279. The prior limitation stemmed from treating the 16-bit symbol section number as signed, whereas modern compilers like MSVC and Clang support the full unsigned range. The solution correctly decodes and encodes these numbers as unsigned, while explicitly preserving special reserved values (undefined, absolute, debug). Additionally, it enhances input validation by rejecting malformed reserved section numbers earlier in the process and includes new test cases for gas and binutil…
- PE/COFF
- An object file format used by Windows, combining aspects of the COFF format with PE (Portable Executable) headers.
- section number
- An identifier for a section within an object file. In PE/COFF symbol tables, this number refers to the section to which a symbol belongs.
- symbol table
- A data structure within an object file that stores information about symbols (e.g., function and variable names, their addresses, and types).
- MSVC
- Microsoft Visual C++, a suite of programming tools for the Microsoft Windows platform, including a compiler and debugger.
- Clang
- A compiler front-end for the C, C++, Objective-C, and Objective-C++ languages, part of the LLVM project.
- gas
- The GNU Assembler, the default assembler used by the GNU Compiler Collection (GCC).
- objdump
- A utility that displays information from object files, including disassembly and symbol tables.