DFSan's shadow mappings are incompatible with 32 bits of ASLR entropy
('sudo sysctl vm.mmap_rnd_bits=32; ninja check-dfsan') and it is
difficult to fix this via increasing the size of the shadow mappings,
due to the overhead of shadow memory. This patch works around the issue
by detecting if the memory layout is incompatible, and if so,
re-exec'ing without ASLR.
DFSan and MSan share copy-pasted shadow memory code, hence this
workaround is ported from MSan:
- "[msan] Re-exec with no ASLR if memory layout is incompatible on
Linux"
(58f7251820)
- "[msan] Add 'MappingDesc::ALLOCATOR' type and check it is available"
(af2bf86a37)
(which in turn are inspired by TSan: "Re-exec TSan with no ASLR if
memory layout is incompatible on Linux"
(0784b1eefa
))
aeubanks had remarked in
https://github.com/llvm/llvm-project/pull/85142#issuecomment-2004442883
that this issue occurs in Chromium:
https://ci.chromium.org/ui/p/chromium/builders/try/linux_upload_clang/5066/overview
The primary motivation for this change is to allow FreeHooks to obtain
the allocated size of the pointer being freed in a fast, efficient manner.
Differential Revision: https://reviews.llvm.org/D151360
D147005 introduced __sanitizer_get_allocated_begin, with a return
value of void*. This involved a few naughty casts that dropped the
const. This patch adds back the const qualifier.
Differential Revision: https://reviews.llvm.org/D147489
compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake:ALL_DFSAN_SUPPORTED_ARCH
allows AArch64 but currently the instrumentation will crash.
Port Linux AArch64 memory mappings from msan but use
SizeClassAllocator64 for a slightly more efficient allocator (used by
asan/lsan). Change dfsan/lit.cfg.py to allow Linux aarch64. All tests
should pass.
* dfsan/origin_invalid.c uses x86_64 assembly. Just make it x86_64 specific.
* dfsan/interceptors.c our mallinfo interceptor takes an argument
instead of returning a struct. This does not work on AArch64 which
uses different registers for the two function types. Disable AArch64
as msan/Linux/mallinfo.cpp does.
Reviewed By: #sanitizers, vitalybuka
Differential Revision: https://reviews.llvm.org/D140770
