tree 09fcb9775089976272611c164e181b1186b99a18
parent d2aa037c4eb97bfad259cc67c954b0870911f2b7
author Peter Collingbourne <peter@pcc.me.uk> 1595450714 -0700
committer Christopher Ferris <cferris@google.com> 1595625199 -0700

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

GitOrigin-RevId: b83417aa7e26ca76c433ec5befdecd5c571408a6
Change-Id: Ie468f0952759da11d72db9b7fa9ba7b353fd6125
Merged-In: Ie468f0952759da11d72db9b7fa9ba7b353fd6125
(cherry picked from commit 10a30f4fa9db3092b8655cf7fda41f29c1ffe45f)