[all-commits] [llvm/llvm-project] b83417: scudo: Interleave odd and even tags for adjacent b...

[pcc via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: b83417aa7e26ca76c433ec5befdecd5c571408a6
      https://github.com/llvm/llvm-project/commit/b83417aa7e26ca76c433ec5befdecd5c571408a6
  Author: Peter Collingbourne <peter at pcc.me.uk>
  Date:   2020-07-23 (Thu, 23 Jul 2020)

  Changed paths:
    M compiler-rt/lib/scudo/standalone/combined.h
    M compiler-rt/lib/scudo/standalone/include/scudo/interface.h
    M compiler-rt/lib/scudo/standalone/memtag.h
    M compiler-rt/lib/scudo/standalone/tests/combined_test.cpp
    M compiler-rt/lib/scudo/standalone/tests/wrappers_c_test.cpp
    M compiler-rt/lib/scudo/standalone/wrappers_c.h
    M compiler-rt/lib/scudo/standalone/wrappers_c.inc

  Log Message:
  -----------
  scudo: Interleave odd and even tags for adjacent blocks.

This guarantees that we will detect a buffer overflow or underflow
that overwrites an adjacent block. This spatial guarantee is similar
to the temporal guarantee that we provide for immediate use-after-free.

Enabling odd/even tags involves a tradeoff between use-after-free
detection and buffer overflow detection. Odd/even tags make it more
likely for buffer overflows to be detected by increasing the size of
the guaranteed "red zone" around the allocation, but on the other
hand use-after-free is less likely to be detected because the tag
space for any particular chunk is cut in half. Therefore we introduce
a tuning setting to control whether odd/even tags are enabled.

Differential Revision: https://reviews.llvm.org/D84361