Adds a new allocation API to GWP-ASan that handles size+alignment
restrictions.
Reviewed By: cryptoad, eugenis
Differential Revision: https://reviews.llvm.org/D94830
Unwinders (like libc's backtrace()) can call their own locks (like the
libdl lock). We need to let the unwinder release the locks before
forking. Wrap a new lock around the unwinder for atfork protection.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D95889
The LateInit test might be reusing some already initialized thread
specific data if run within the main thread. This means that there
is a chance that the current value will not be enough for the 100
iterations, hence the test flaking.
Fix this by making the test run in its own thread.
Differential Revision: https://reviews.llvm.org/D92415
In a similar fashion to D87420 for Scudo, this CL introduces a way to
get thread local variables via a platform-specific reserved TLS slot,
since Fuchsia doesn't support ELF TLS from the libc itself.
If needing to use this, a platform will have to define
`GWP_ASAN_HAS_PLATFORM_TLS_SLOT` and provide `gwp_asan_platform_tls_slot.h`
which will define a `uint64_t *getPlatformGwpAsanTlsSlot()` function
that will return the TLS word of storage.
I snuck in a couple of cleanup items as well, moving some static
functions to anonymous namespace for consistency.
Differential Revision: https://reviews.llvm.org/D90195
In preparation for Fuchsia support, this CL refactors the memory
mapping functions.
The new functions are as follows:
- for Freeslots and Metadata:
`void *map(size_t Size, const char *Name) const;`
`void unmap(void *Ptr, size_t Size) const;`
- for the Pool:
`void *reservePool(size_t Size);`
`void commitPool(void *Ptr, size_t Size) const;`
`void decommitPool(void *Ptr, size_t Size) const;`
`void unreservePool();`
Note that those don't need a `Name` parameter as those are fixed per
function. `{reserve,unreserve}Pool` are not `const` because they will
modify platform specific class member on Fuchsia.
I added a plethora of `assert()` as the initial code was not enforcing
page alignment for sizes and addresses, which caused problem in the
initial Fuchsia draft. All sizes should now be properly rounded up to
a page.
Differential Revision: https://reviews.llvm.org/D89993
This is a redo of D89908, which triggered some `-Werror=conversion`
errors with GCC due to assignments to the 31-bit variable.
This CL adds to the original one a 31-bit mask variable that is used
at every assignment to silence the warning.
Differential Revision: https://reviews.llvm.org/D89984
This reverts commit 9903b0586c.
Causes build failures (on GCC 10.2) with the following error:
In file included from /home/nikic/llvm-project/compiler-rt/lib/scudo/standalone/combined.h:29,
from /home/nikic/llvm-project/compiler-rt/lib/scudo/standalone/allocator_config.h:12,
from /home/nikic/llvm-project/compiler-rt/lib/scudo/standalone/wrappers_cpp.cpp:14:
/home/nikic/llvm-project/compiler-rt/lib/scudo/standalone/../../gwp_asan/guarded_pool_allocator.h: In member function ‘bool gwp_asan::GuardedPoolAllocator::shouldSample()’:
/home/nikic/llvm-project/compiler-rt/lib/scudo/standalone/../../gwp_asan/guarded_pool_allocator.h:82:69: error: conversion from ‘uint32_t’ {aka ‘unsigned int’} to ‘unsigned int:31’ may change value [-Werror=conversion]
82 | (getRandomUnsigned32() % (AdjustedSampleRatePlusOne - 1)) + 1;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
We need to have all thread specific data packed into a single `uintptr_t`
for the upcoming Fuchsia support. We can move the `RandomState` into the
`ThreadLocalPackedVariables`, reducing the size of `NextSampleCounter`
to 31 bits (or we could reduce `RandomState` to 31 bits).
We move `getRandomUnsigned32` into the platform agnostic part of the
class, and `initPRNG` in the platform specific part.
`ScopedBoolean` is replaced by actual assignments since non-const
references to bitfields are prohibited.
`random.{h,cpp}` are removed.
Differential Revision: https://reviews.llvm.org/D89908
Summary:
GWP-ASan's PRNG didn't use Initial-Exec TLS. Fix that to ensure that we don't
have infinite recursion, and also that we don't allocate a DTV on Android when
GWP-ASan is touched.
Test coverage ensuring that the sample counter is UINT32_MAX for an
uninitialised GWP-ASan is provided by gwp_asan/tests/late_init.cpp.
Reviewers: pcc, cferris
Reviewed By: pcc
Subscribers: #sanitizers, llvm-commits, rprichard, eugenis
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D74135
Summary:
Forewarning: This patch looks big in #LOC changed. I promise it's not that bad, it just moves a lot of content from one file to another. I've gone ahead and left inline comments on Phabricator for sections where this has happened.
This patch:
1. Introduces the crash handler API (crash_handler_api.h).
2. Moves information required for out-of-process crash handling into an AllocatorState. This is a trivially-copied POD struct that designed to be recovered from a deceased process, and used by the crash handler to create a GWP-ASan report (along with the other trivially-copied Metadata struct).
3. Implements the crash handler API using the AllocatorState and Metadata.
4. Adds tests for the crash handler.
5. Reimplements the (now optionally linked by the supporting allocator) in-process crash handler (i.e. the segv handler) using the new crash handler API.
6. Minor updates Scudo & Scudo Standalone to fix compatibility.
7. Changed capitalisation of errors (e.g. /s/Use after free/Use After Free).
Reviewers: cryptoad, eugenis, jfb
Reviewed By: eugenis
Subscribers: merge_guards_bot, pcc, jfb, dexonsmith, mgorny, cryptoad, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73557
Summary:
This patch allows for late initialisation of the GWP-ASan allocator. Previously, if late initialisation occurred, the sample counter was never updated, meaning we would end up having to wait for 2^32 allocations before getting a sampled allocation.
Now, we initialise the sampling mechanism in init() as well. We require init() to be called single-threaded, so this isn't a problem.
Reviewers: eugenis
Reviewed By: eugenis
Subscribers: merge_guards_bot, mgorny, #sanitizers, llvm-commits, cferris
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73896
Summary:
This is an Android-specific interface for iterating over all live
allocations in a memory range.
Reviewers: hctim, cferris
Subscribers: mgorny, mgrang, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73305
Summary:
* Implement enable() and disable() in GWP-ASan.
* Setup atfork handler.
* Improve test harness sanity and re-enable GWP-ASan in Scudo.
Scudo_standalone disables embedded GWP-ASan as necessary around fork().
Standalone GWP-ASan sets the atfork handler in init() if asked to. This
requires a working malloc(), therefore GWP-ASan initialization in Scudo
is delayed to the post-init callback.
Test harness changes are about setting up a single global instance of
the GWP-ASan allocator so that pthread_atfork() does not create
dangling pointers.
Test case shamelessly stolen from D72470.
Reviewers: cryptoad, hctim, jfb
Subscribers: mgorny, jfb, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D73294
Summary:
GWP-ASan test currently fail on 32-bit platforms, as some of the pointers are
larger than `uintptr_t` on 32-bit platforms. Fix up all those instances.
Also add an uncompress varint test where the result is an underflow.
Furthermore, allow multi-init for testing. Each gtest when running
`check-gwp_asan` apparently runs in its own instance, but when integrating
these tests into Android, this behaviour isn't the same. We remove the
global multi-init check here, to allow for testing to work elsewhere, and we're
not really worried about multi-init anyway as it's part of our contract with
the allocator.
Reviewers: eugenis, vlad.tsyrklevich
Reviewed By: eugenis
Subscribers: #sanitizers, llvm-commits, pcc
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D71121
Summary:
When platforms use their own `LIKELY()` definitions, it can be quite
troublesome to ensure they don't conflict with the GWP-ASan internal
definitions. Just force the GWP_ASAN_ prefix to help this issue.
Reviewers: eugenis
Reviewed By: eugenis
Subscribers: #sanitizers, llvm-commits, cferris, pcc
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D70683
Summary:
This patch introduces stack frame compression to GWP-ASan. Each stack frame is
variable-length integer encoded as the difference between frame[i] and
frame[i - 1]. Furthermore, we use zig-zag encoding on the difference to ensure
that negative differences are also encoded into a relatively small number of
bytes.
Examples of what the compression looks like can be seen in
`gwp_asan/tests/compression.cpp`.
This compression can reduce the memory consumption cost of stack traces by
~50%.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: mgorny, #sanitizers, llvm-commits, eugenis, morehouse
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D66189
llvm-svn: 369048
Summary:
Updates the function signature and comments for backtracing (and printing
backtraces). This update brings GWP-ASan in line with future requirements for
stack frame compression, wherein the length of the trace is provided
explicitly, rather than relying on nullptr-termination.
Reviewers: vlad.tsyrklevich
Reviewed By: vlad.tsyrklevich
Subscribers: #sanitizers, llvm-commits, morehouse
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D66099
llvm-svn: 368619
Summary:
Adds two flavours of generic unwinder and all the supporting cruft. If the
supporting allocator is okay with bringing in sanitizer_common, they can use
the fast frame-pointer based unwinder from sanitizer_common. Otherwise, we also
provide the backtrace() libc-based unwinder as well. Of course, the allocator
can always specify its own unwinder and unwinder-symbolizer.
The slightly changed output format is exemplified in the first comment on this
patch. It now better incorporates backtrace information, and displays
allocation details on the second line.
Reviewers: eugenis, vlad.tsyrklevich
Reviewed By: eugenis, vlad.tsyrklevich
Subscribers: srhines, kubamracek, mgorny, cryptoad, #sanitizers, llvm-commits, morehouse
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D63841
llvm-svn: 364941
Summary:
Add a recursivity guard for GPA::allocate(). This means that any
recursive allocations will fall back to the supporting allocator. In future
patches, we will introduce stack trace collection support. The unwinder will be
provided by the supporting allocator, and we can't guarantee they don't call
malloc() (e.g. backtrace() on posix may call dlopen(), which may call malloc().
Furthermore, this patch packs the new TLS recursivity guard into a thread local
struct, so that TLS variables should be hopefully not fall across cache lines.
Reviewers: vlad.tsyrklevich, morehouse, eugenis
Reviewed By: eugenis
Subscribers: kubamracek, #sanitizers, llvm-commits, eugenis
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D63736
llvm-svn: 364356
Summary:
See D60593 for further information.
This patch introduces the core of GWP-ASan, being the guarded pool allocator. This class contains the logic for creating and maintaining allocations in the guarded pool. Its public interface is to be utilised by supporting allocators in order to provide sampled guarded allocation behaviour.
This patch also contains basic functionality tests of the allocator as unittests. The error-catching behaviour will be tested in upcoming patches that use Scudo as an implementing allocator.
Reviewers: vlad.tsyrklevich, eugenis, jfb
Reviewed By: vlad.tsyrklevich
Subscribers: dexonsmith, kubamracek, mgorny, cryptoad, jfb, #sanitizers, llvm-commits, morehouse
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D62872
llvm-svn: 362636
Mitch Phillips