The problem is similar to D55986 but for threads: a process with the
interceptor hwasan library loaded might have some threads started by
instrumented libraries and some by uninstrumented libraries, and we
need to be able to run instrumented code on the latter.
The solution is to perform per-thread initialization lazily. If a
function needs to access shadow memory or add itself to the per-thread
ring buffer its prologue checks to see whether the value in the
sanitizer TLS slot is null, and if so it calls __hwasan_thread_enter
and reloads from the TLS slot. The runtime does the same thing if it
needs to access this data structure.
This change means that the code generator needs to know whether we
are targeting the interceptor runtime, since we don't want to pay
the cost of lazy initialization when targeting a platform with native
hwasan support. A flag -fsanitize-hwaddress-abi={interceptor,platform}
has been introduced for selecting the runtime ABI to target. The
default ABI is set to interceptor since it's assumed that it will
be more common that users will be compiling application code than
platform code.
Because we can no longer assume that the TLS slot is initialized,
the pthread_create interceptor is no longer necessary, so it has
been removed.
Ideally, lazy initialization should only cost one instruction in the
hot path, but at present the call may cause us to spill arguments
to the stack, which means more instructions in the hot path (or
theoretically in the cold path if the spills are moved with shrink
wrapping). With an appropriately chosen calling convention for
the per-thread initialization function (TODO) the hot path should
always need just one instruction and the cold path should need two
instructions with no spilling required.
Differential Revision: https://reviews.llvm.org/D56038
llvm-svn: 350429
The Android dynamic loader has a non-standard feature that allows
libraries such as the hwasan runtime to interpose symbols even after
the symbol already has a value. The new value of the symbol is used to
relocate libraries loaded after the interposing library, but existing
libraries keep the old value. This behaviour is activated by the
DF_1_GLOBAL flag in DT_FLAGS_1, which is set by passing -z global to
the linker, which is what we already do to link the hwasan runtime.
What this means in practice is that if we have .so files that depend
on interceptor-mode hwasan without the main executable depending on
it, some of the libraries in the process will be using the hwasan
allocator and some will be using the system allocator, and these
allocators need to interact somehow. For example, if an instrumented
library calls a function such as strdup that allocates memory on
behalf of the caller, the instrumented library can reasonably expect
to be able to call free to deallocate the memory.
We can handle that relatively easily with hwasan by using tag 0 to
represent allocations from the system allocator. If hwasan's realloc
or free functions are passed a pointer with tag 0, the system allocator
is called.
One limitation is that this scheme doesn't work in reverse: if an
instrumented library allocates memory, it must free the memory itself
and cannot pass ownership to a system library. In a future change,
we may want to expose an API for calling the system allocator so
that instrumented libraries can safely transfer ownership of memory
to system libraries.
Differential Revision: https://reviews.llvm.org/D55986
llvm-svn: 350427
Summary:
Add a check that TLS_SLOT_TSAN / TLS_SLOT_SANITIZER, whichever
android_get_tls_slot is using, is not conflicting with
TLS_SLOT_DLERROR.
Reviewers: rprichard, vitalybuka
Subscribers: srhines, kubamracek, llvm-commits
Differential Revision: https://reviews.llvm.org/D55587
llvm-svn: 348979
Summary:
When reporting a fatal error, collect and add the entire report text to
android_set_abort_message so that it can be found in the tombstone.
Reviewers: kcc, vitalybuka
Subscribers: srhines, kubamracek, llvm-commits
Differential Revision: https://reviews.llvm.org/D54284
llvm-svn: 346557
Summary:
GetStackTrace treats top PC as a return address from an error reporting
function, and adjusts it down by 1 instruction. This is not necessary in
a signal handler, so adjust PC up to compensate.
Reviewers: kcc, vitalybuka, jfb
Subscribers: kubamracek, llvm-commits
Differential Revision: https://reviews.llvm.org/D52802
llvm-svn: 343638
Summary:
Display a list of recent stack frames (not a stack trace!) when
tag-mismatch is detected on a stack address.
The implementation uses alignment tricks to get both the address of
the history buffer, and the base address of the shadow with a single
8-byte load. See the comment in hwasan_thread_list.h for more
details.
Developed in collaboration with Kostya Serebryany.
Reviewers: kcc
Subscribers: srhines, kubamracek, mgorny, hiraditya, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52249
llvm-svn: 342923
Summary:
Display a list of recent stack frames (not a stack trace!) when
tag-mismatch is detected on a stack address.
The implementation uses alignment tricks to get both the address of
the history buffer, and the base address of the shadow with a single
8-byte load. See the comment in hwasan_thread_list.h for more
details.
Developed in collaboration with Kostya Serebryany.
Reviewers: kcc
Subscribers: srhines, kubamracek, mgorny, hiraditya, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52249
llvm-svn: 342921
Summary:
The idea behind this change is to allow sanitization of libc. We are prototyping on Bionic,
but the tool interface will be general enough (or at least generalizable) to support any other libc.
When libc depends on libclang_rt.hwasan, the latter can not interpose libc functions.
In fact, majority of interceptors become unnecessary when libc code is instrumented.
This change gets rid of most hwasan interceptors and provides interface for libc to notify
hwasan about thread creation and destruction events. Some interceptors (pthread_create)
are kept under #ifdef to enable testing with uninstrumented libc. They are expressed in
terms of the new libc interface.
The new cmake switch, COMPILER_RT_HWASAN_WITH_INTERCEPTORS, ON by default, builds testing
version of the library with the aforementioned pthread_create interceptor.
With the OFF setting, the library becomes more of a libc plugin.
Reviewers: vitalybuka, kcc, jfb
Subscribers: srhines, kubamracek, mgorny, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D50922
llvm-svn: 340216
Summary:
Provide __hwasan_shadow_init that can be used to initialize shadow w/o touching libc.
It can be used to bootstrap an unusual case of fully-static executable with
hwasan-instrumented libc, which needs to run hwasan code before it is ready to serve
user calls like madvise().
Reviewers: vitalybuka, kcc
Subscribers: kubamracek, llvm-commits
Differential Revision: https://reviews.llvm.org/D50581
llvm-svn: 339606
MmapFixedNoReserve does not terminate process on failure.
Failure to check its result and die will always lead to harder
to debug crashes later in execution. This was observed in Go
processes due to some address space conflicts.
Consistently check result of MmapFixedNoReserve.
While we are here also add warn_unused_result attribute
to prevent such bugs in future and change return type to bool
as that's what all callers want.
Reviewed in https://reviews.llvm.org/D49367
llvm-svn: 337531
Summary:
Currently many allocator specific errors (OOM, for example) are reported as
a text message and CHECK(0) termination, not stack, no details, not too
helpful nor informative. To improve the situation, detailed and
structured errors were defined and reported under the appropriate conditions.
Reviewers: eugenis
Subscribers: kubamracek, delcypher, llvm-commits, #sanitizers
Differential Revision: https://reviews.llvm.org/D47798
llvm-svn: 334248
Retire the fixed shadow memory mapping to avoid conflicts with default
process memory mapping (currently manifests on Android).
Tests on AArch64 show <1% performance loss and code size increase,
making it possible to use dynamic shadow memory by default.
Keep the fixed shadow memory mapping around to be able to run
performance comparison tests later.
Re-commiting D45847 with fixed shadow for x86-64.
llvm-svn: 330624
This commit causes internal errors with ld.bfd 2.24. My guess is that
the ifunc usage in this commit is causing problems. This is the default
system linker on Trusty Tahr, which is from 2014. I claim it's still in
our support window. Maybe we will decide to drop support for it, but
let's get the bots green while we do the investigation and have that
discussion.
Discovered here: https://crbug.com/835864
llvm-svn: 330619
Summary:
Retire the fixed shadow memory mapping to avoid conflicts with default
process memory mapping (currently manifests on Android).
Tests on AArch64 show <1% performance loss and code size increase,
making it possible to use dynamic shadow memory by default.
For the simplicity and unifirmity sake, use dynamic shadow memory mapping
with base address accessed via ifunc resolver on all supported platforms.
Keep the fixed shadow memory mapping around to be able to run
performance comparison tests later.
Complementing D45840.
Reviewers: eugenis
Subscribers: srhines, kubamracek, dberris, mgorny, kristof.beyls, delcypher, #sanitizers, llvm-commits
Differential Revision: https://reviews.llvm.org/D45847
llvm-svn: 330474
Summary:
Porting HWASan to Linux x86-64, first of the three patches, compiler-rt part.
The approach is similar to ARM case, trap signal is used to communicate
memory tag check failure. int3 instruction is used to generate a signal,
access parameters are stored in nop [eax + offset] instruction immediately
following the int3 one
Had to add HWASan init on malloc because, due to much less interceptors
defined (most other sanitizers intercept much more and get initalized
via one of those interceptors or don't care about malloc), HWASan was not
initialized yet when libstdc++ was trying to allocate memory for its own
fixed-size heap, which led to CHECK-fail in AllocateFromLocalPool.
Also added the CHECK() failure handler with more detailed message and
stack reporting.
Reviewers: eugenis
Subscribers: kubamracek, dberris, mgorny, kristof.beyls, delcypher, #sanitizers, llvm-commits
Differential Revision: https://reviews.llvm.org/D44705
llvm-svn: 328385
This patch changes hwasan inline instrumentation:
Fixes address untagging for shadow address calculation (use 0xFF instead of 0x00 for the top byte).
Emits brk instruction instead of hlt for the kernel and user space.
Use 0x900 instead of 0x100 for brk immediate (0x100 - 0x800 are unavailable in the kernel).
Fixes and adds appropriate tests.
Patch by Andrey Konovalov.
Differential Revision: https://reviews.llvm.org/D43135
llvm-svn: 325711
Summary:
Very basic stack instrumentation using tagged pointers.
Tag for N'th alloca in a function is built as XOR of:
* base tag for the function, which is just some bits of SP (poor
man's random)
* small constant which is a function of N.
Allocas are aligned to 16 bytes. On every ReturnInst allocas are
re-tagged to catch use-after-return.
This implementation has a bunch of issues that will be taken care of
later:
1. lifetime intrinsics referring to tagged pointers are not
recognized in SDAG. This effectively disables stack coloring.
2. Generated code is quite inefficient. There is one extra
instruction at each memory access that adds the base tag to the
untagged alloca address. It would be better to keep tagged SP in a
callee-saved register and address allocas as an offset of that XOR
retag, but that needs better coordination between hwasan
instrumentation pass and prologue/epilogue insertion.
3. Lifetime instrinsics are ignored and use-after-scope is not
implemented. This would be harder to do than in ASan, because we
need to use a differently tagged pointer depending on which
lifetime.start / lifetime.end the current instruction is dominated
/ post-dominated.
Reviewers: kcc, alekseyshl
Subscribers: srhines, kubamracek, javed.absar, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D41602
llvm-svn: 322324
Summary: Very similar to AddressSanitizer, with the exception of the error type encoding.
Reviewers: kcc, alekseyshl
Subscribers: cfe-commits, kubamracek, llvm-commits, hiraditya
Differential Revision: https://reviews.llvm.org/D41417
llvm-svn: 321203
Summary: This brings CPU overhead on bzip2 down from 5.5x to 2x.
Reviewers: kcc, alekseyshl
Subscribers: kubamracek, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D41137
llvm-svn: 320538
Peter Collingbourne