This is a part of https://reviews.llvm.org/D95835.
This change is to address two problems
1) When recording stacks in origin tracking, libunwind is not async signal safe. Inside signal callbacks, we need
to use fast unwind. Fast unwind needs threads
2) StackDepot used by origin tracking is not async signal safe, we set a flag per thread inside
a signal callback to prevent from using it.
The thread registration is similar to ASan and MSan.
Related MSan changes are
* 98f5ea0dba
* f653cda269
* 5a7c364343
Some changes in the diff are used in the next diffs
1) The test case pthread.c is not very interesting for now. It will be
extended to test origin tracking later.
2) DFsanThread::InSignalHandler will be used by origin tracking later.
Reviewed-by: morehouse
Differential Revision: https://reviews.llvm.org/D95963
DFSan uses TLS to pass metadata of arguments and return values. When an
instrumented function accesses the TLS, if a signal callback happens, and
the callback calls other instrumented functions with updating the same TLS,
the TLS is in an inconsistent state after the callback ends. This may cause
either under-tainting or over-tainting.
This fix follows MSan's workaround.
cb22c67a21
It simply resets TLS at restore. This prevents from over-tainting. Although
under-tainting may still happen, a taint flow can be found eventually if we
run a DFSan-instrumented program multiple times. The alternative option is
saving the entire TLS. However the TLS storage takes 2k bytes, and signal calls
could be nested. So it does not seem worth.
This diff fixes sigaction. A following diff will be fixing signal.
Reviewed-by: morehouse
Differential Revision: https://reviews.llvm.org/D95642
The wrapper clears shadow for addr and addrlen when written to.
Reviewed By: stephan.yichao.zhao
Differential Revision: https://reviews.llvm.org/D93046
The wrapper clears shadow for any bytes written to addr or addrlen.
Reviewed By: stephan.yichao.zhao
Differential Revision: https://reviews.llvm.org/D92964
The wrapper clears shadow for optval and optlen when written.
Reviewed By: stephan.yichao.zhao, vitalybuka
Differential Revision: https://reviews.llvm.org/D92961
base and nptr_label were swapped, which meant we were passing nptr's
shadow as the base to the operation. Usually, the shadow is 0, which
causes strtoull to guess the correct base from the string prefix (e.g.,
0x means base-16 and 0 means base-8), hiding this bug. Adjust the test
case to expose the bug.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D85935
Vitaly Buka