A heap or global buffer that is far away from the faulting address is
unlikely to be the cause, especially if there is a potential
use-after-free as well, so we want to show it after the other
causes.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D104781
Userspace page aliasing allows us to use middle pointer bits for tags
without untagging them before syscalls or accesses. This should enable
easier experimentation with HWASan on x86_64 platforms.
Currently stack, global, and secondary heap tagging are unsupported.
Only primary heap allocations get tagged.
Note that aliasing mode will not work properly in the presence of
fork(), since heap memory will be shared between the parent and child
processes. This mode is non-ideal; we expect Intel LAM to enable full
HWASan support on x86_64 in the future.
Reviewed By: vitalybuka, eugenis
Differential Revision: https://reviews.llvm.org/D98875
Userspace page aliasing allows us to use middle pointer bits for tags
without untagging them before syscalls or accesses. This should enable
easier experimentation with HWASan on x86_64 platforms.
Currently stack, global, and secondary heap tagging are unsupported.
Only primary heap allocations get tagged.
Note that aliasing mode will not work properly in the presence of
fork(), since heap memory will be shared between the parent and child
processes. This mode is non-ideal; we expect Intel LAM to enable full
HWASan support on x86_64 in the future.
Reviewed By: vitalybuka, eugenis
Differential Revision: https://reviews.llvm.org/D98875
Subsequent patches will implement page-aliasing mode for x86_64, which
will initially only work for the primary heap allocator. We force
callback instrumentation to simplify the initial aliasing
implementation.
Reviewed By: vitalybuka, eugenis
Differential Revision: https://reviews.llvm.org/D98069
Once we start instrumenting globals, all addresses including those of string literals
that we pass to the operating system will start being tagged. Since we can't rely
on the operating system to be able to cope with these addresses, we need to untag
them before passing them to the operating system. This change introduces a macro
that does so and uses it everywhere it is needed.
Differential Revision: https://reviews.llvm.org/D65768
llvm-svn: 367938
Summary:
Replace the 32-bit allocator with a 64-bit one with a non-constant
base address, and reduce both the number of size classes and the maximum
size of per-thread caches.
As measured on [1], this reduces average weighted memory overhead
(MaxRSS) from 26% to 12% over stock android allocator. These numbers
include overhead from code instrumentation and hwasan shadow (i.e. not a
pure allocator benchmark).
This switch also enables release-to-OS functionality, which is not
implemented in the 32-bit allocator. I have not seen any effect from
that on the benchmark.
[1] https://android.googlesource.com/platform/system/extras/+/master/memory_replay/
Reviewers: vitalybuka, kcc
Subscribers: kubamracek, cryptoad, llvm-commits
Differential Revision: https://reviews.llvm.org/D56239
llvm-svn: 350370
Summary:
... so that we can find intra-granule buffer overflows.
The default is still to always align left.
It remains to be seen wether we can enable this mode at scale.
Reviewers: eugenis
Reviewed By: eugenis
Subscribers: jfb, dvyukov, kubamracek, delcypher, #sanitizers, llvm-commits
Differential Revision: https://reviews.llvm.org/D53789
llvm-svn: 347082
To minimize testing surface (remove libstdc++ from the picture, for
one), make use-after-free c, not c++ test.
Differential Revision: https://reviews.llvm.org/D44705
llvm-svn: 328646
Florian Mayer