[all-commits] [llvm/llvm-project] 535520: [llvm-objcopy] --gap-fill and 0-size sections (#75...

[quic-akaryaki via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 535520c6636f9a2bd7cd8fcb221e598a372cae9e
      https://github.com/llvm/llvm-project/commit/535520c6636f9a2bd7cd8fcb221e598a372cae9e
  Author: quic-akaryaki <123192073+quic-akaryaki at users.noreply.github.com>
  Date:   2023-12-19 (Tue, 19 Dec 2023)

  Changed paths:
    M llvm/lib/ObjCopy/ELF/ELFObject.cpp
    M llvm/test/tools/llvm-objcopy/ELF/gap-fill.test

  Log Message:
  -----------
  [llvm-objcopy] --gap-fill and 0-size sections (#75837)

In the change that added `--gap-fill`, the condition to choose the
sections to write in `BinaryWriter::write()` did not exclude zero-size
sections. However, zero-size sections did not have correct offsets
assigned in `BinaryWriter::finalize()`. The result is either a failed
assertion, or memory corruption due to writing to the buffer beyond its
size.
To fix this, exclude zero-size sections from writing. Also, add a zero-size
section to the test, which would trigger the problem.