This CL modifies the PlatformUnpoisonStacks so that fuchsia can
implement its own logic for unpoisoning the stacks.
For the general case, the behavior is the same as with regular asan: it
will unpoison everything from the current stack pointer until the base
of the stack (stack top).
In some situations, the current stack might not be the same as the
default stack. In those cases, the code will now unpoison the entire
default stack, and will also unpoison the current page of the stack.
Reviewed By: mcgrathr
Differential Revision: https://reviews.llvm.org/D106835
When enabling stack use-after-free detection, we discovered that we read
the thread ID on the main thread while it is still set to 2^24-1.
This patch moves our call to AsanThread::Init() out of CreateAsanThread,
so that we can call SetCurrentThread first on the main thread.
Reviewed By: mcgrathr
Differential Revision: https://reviews.llvm.org/D89606
This reverts commit 0caad9fe44.
This reverts commit c96d0cceb6.
Causes linker errors which were not fixed by the subsequent commit
either:
/home/nikic/llvm-project/compiler-rt/lib/asan/asan_rtl.cpp:503: error: undefined reference to '__asan::InstallAtExitCheckLeaks()'
Fuchsia's system libraries are instrumented and use the lsan
allocator for internal purposes. So leak checking needs to run
after all atexit hooks and after the system libraries' internal
exit-time hooks. The <zircon/sanitizer.h> hook API calls the
__sanitizer_process_exit_hook function at exactly the right time.
Reviewed By: vitalybuka, phosek
Differential Revision: https://reviews.llvm.org/D86171
This CL allows asan allocator in fuchsia to decommit shadow memory
for memory allocated using mmap.
Big allocations in asan end up being allocated via `mmap` and freed with
`munmap`. However, when that memory is freed, asan returns the
corresponding shadow memory back to the OS via a call to
`ReleaseMemoryPagesToOs`.
In fuchsia, `ReleaseMemoryPagesToOs` is a no-op: to be able to free
memory back to the OS, you have to hold a handle to the vmo you want to
modify, which is tricky at the ReleaseMemoryPagesToOs level as that
function is not exclusively used for shadow memory.
The function `__sanitizer_fill_shadow` fills a given shadow memory range
with a specific value, and if that value is 0 (unpoison) and the memory
range is bigger than a threshold parameter, it will decommit that memory
if it is all zeroes.
This CL modifies the `FlushUnneededASanShadowMemory` function in
`asan_poisoning.cpp` to add a call to `__sanitizer_fill_shadow` with
value and threshold = 0. This way, all the unneeded shadow memory gets
returned back to the OS.
A test for this behavior can be found in fxrev.dev/391974
Differential Revision: https://reviews.llvm.org/D80355
Change-Id: Id6dd85693e78a222f0329d5b2201e0da753e01c0
Summary: This adds a customization point to support unpoisoning of signal alternate stacks on POSIX.
Reviewers: vitalybuka
Reviewed By: vitalybuka
Subscribers: #sanitizers
Tags: #sanitizers
Differential Revision: https://reviews.llvm.org/D81577
Marco Vanotti