tree 438b2d7f68e6be4852b5c866503a0ca1c09dfa57
parent 4079a1c1f02525415bea11cdaf804fb7635c7de8
author Mitch Phillips <31459023+hctim@users.noreply.github.com> 1673470538 -0800
committer Copybara-Service <copybara-worker@google.com> 1673471728 -0800

[GWP-ASan] Add recoverable mode.

The GWP-ASan recoverable mode allows a process to continue to function
after a GWP-ASan error is detected. The error will continue to be
dumped, but GWP-ASan now has APIs that a signal handler (like the
example optional crash handler) can call in order to allow the
continuation of a process.

When an error occurs with an allocation, the slot used for that
allocation will be permanently disabled. This means that free() of that
pointer is a no-op, and use-after-frees will succeed (writing and
reading the data present in the page).

For heap-buffer-overflow/underflow, the guard page is marked as accessible
and buffer-overflows will succeed (writing and reading the data present
in the now-accessible guard page). This does impact adjacent
allocations, buffer-underflow and buffer-overflows from adjacent
allocations will no longer touch an inaccessible guard page. This could
be improved in future by having two guard pages between each adjacent
allocation, but that's out of scope of this patch.

Each allocation only ever has a single error report generated. It's
whatever came first between invalid-free, double-free, use-after-free or
heap-buffer-overflow, but only one.

Reviewed By: eugenis, fmayer

Differential Revision: https://reviews.llvm.org/D140173

GitOrigin-RevId: 90a9beb7cc9755791caa23dfc4e36bc544e98ed3