[all-commits] [llvm/llvm-project] 936639: [libunwind] Fix evaluating DWARF operation DW_OP_pick

[Steven Wu via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 9366397f057d18401e680b2cb28a0ee17c59d4a6
      https://github.com/llvm/llvm-project/commit/9366397f057d18401e680b2cb28a0ee17c59d4a6
  Author: Steven Wu <stevenwu at apple.com>
  Date:   2019-12-18 (Wed, 18 Dec 2019)

  Changed paths:
    M libunwind/src/DwarfInstructions.hpp

  Log Message:
  -----------
  [libunwind] Fix evaluating DWARF operation DW_OP_pick

reg is unsigned type and used here for getting array element from the end by
negating it. negation of unsigned can result in large number and array access
with that index will result in segmentation fault.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=43872

Patched by: kamlesh kumar

Differential Revision: https://reviews.llvm.org/D69893