[all-commits] [llvm/llvm-project] ba0e71: Do not map read-only data memory sections with EXE...

[David Turner via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: ba0e71432a60e1fa2da9e098cbc574a1d9b9618b
      https://github.com/llvm/llvm-project/commit/ba0e71432a60e1fa2da9e098cbc574a1d9b9618b
  Author: David Turner <digit at google.com>
  Date:   2020-08-05 (Wed, 05 Aug 2020)

  Changed paths:
    M llvm/lib/ExecutionEngine/SectionMemoryManager.cpp

  Log Message:
  -----------
  Do not map read-only data memory sections with EXECUTE flags.

The code in SectionMemoryManager.cpp unnecessarily maps
read-only data sections with the READ+EXECUTE flags. This is
undesirable from a security stand-point.

Moreover, on the Fuchsia platform, which is now very strict
about mapping pages with the EXECUTE permission, this simply
fails, because the section's pages were initially allocated
with only the READ+WRITE flags.

A more detailed description of the issue can be found in this
public SwiftShader bug:

  https://issuetracker.google.com/issues/154586551

This patch just restrict the mapping to the READ flag for ROData
sections. Code sections are still mapped with READ+EXECUTE as
expected.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D78574