A short granule is a granule of size between 1 and `TG-1` bytes. The size
of a short granule is stored at the location in shadow memory where the
granule's tag is normally stored, while the granule's actual tag is stored
in the last byte of the granule. This means that in order to verify that a
pointer tag matches a memory tag, HWASAN must check for two possibilities:
* the pointer tag is equal to the memory tag in shadow memory, or
* the shadow memory tag is actually a short granule size, the value being loaded
is in bounds of the granule and the pointer tag is equal to the last byte of
the granule.
Pointer tags between 1 to `TG-1` are possible and are as likely as any other
tag. This means that these tags in memory have two interpretations: the full
tag interpretation (where the pointer tag is between 1 and `TG-1` and the
last byte of the granule is ordinary data) and the short tag interpretation
(where the pointer tag is stored in the granule).
When HWASAN detects an error near a memory tag between 1 and `TG-1`, it
will show both the memory tag and the last byte of the granule. Currently,
it is up to the user to disambiguate the two possibilities.
Because this functionality obsoletes the right aligned heap feature of
the HWASAN memory allocator (and because we can no longer easily test
it), the feature is removed.
Also update the documentation to cover both short granule tags and
outlined checks.
Differential Revision: https://reviews.llvm.org/D63908
llvm-svn: 365551
Reports correct size and tags when either size is not power of two
or offset to bad granule is not zero.
Differential revision: https://reviews.llvm.org/D56603
llvm-svn: 351730
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Now that memory intrinsics are instrumented, it's more likely that
CheckAddressSized will be called with size 0. (It was possible before
with IR like:
%val = load [0 x i8], [0 x i8]* %ptr
but I don't think clang will generate IR like that and the optimizer
would normally remove it by the time it got anywhere near our pass
anyway). The right thing to do in both cases is to disable the
addressing checks (since the underlying memory intrinsic is a no-op),
so that's what we do.
Differential Revision: https://reviews.llvm.org/D56465
llvm-svn: 350683
This is patch complements D55117 implementing __hwasan_mem*
functions in runtime
Differential revision: https://reviews.llvm.org/D55554
llvm-svn: 349730
Matt Morehouse