This allows DFSan to find tainted values used to control program behavior.
Reviewed By: morehouse
Differential Revision: https://reviews.llvm.org/D116207
Since glibc 2.34, dlsym does
1. malloc 1
2. malloc 2
3. free pointer from malloc 1
4. free pointer from malloc 2
These sequence was not handled by trivial dlsym hack.
This fixes https://bugs.llvm.org/show_bug.cgi?id=52278
Reviewed By: eugenis, morehouse
Differential Revision: https://reviews.llvm.org/D112588
Writing zeros to shadow (including checking for existing zero) is now ~2x
faster on one example.
Reviewed By: morehouse
Differential Revision: https://reviews.llvm.org/D110733
Enable -Wformat in sanitizer_common now that it's
cleaned up from existing warnings.
But disable it in all sanitizers for now since
they are not cleaned up yet, but inherit sanitizer_common CFLAGS.
Depends on D107980.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D107981
The current (default) line length is 80 columns.
That's based on old hardware and historical conventions.
There are no existent reasons to keep line length that small,
especially provided that our coding style uses quite lengthy
identifiers. The Linux kernel recently switched to 100,
let's start with 100 as well.
This change intentionally does not re-format code.
Re-formatting is intended to happen incrementally,
or on dir-by-dir basis separately.
Reviewed By: vitalybuka, melver, MaskRay
Differential Revision: https://reviews.llvm.org/D106436
This is a second attempt at D101497, which landed as
9a9bc76c0e but had to be reverted in
8cf7ddbdd4.
This issue was that in the case that `COMPILER_RT_INSTALL_PATH` is
empty, expressions like "${COMPILER_RT_INSTALL_PATH}/bin" evaluated to
"/bin" not "bin" as intended and as was originally.
One solution is to make `COMPILER_RT_INSTALL_PATH` always non-empty,
defaulting it to `CMAKE_INSTALL_PREFIX`. D99636 adopted that approach.
But, I think it is more ergonomic to allow those project-specific paths
to be relative the global ones. Also, making install paths absolute by
default inhibits the proper behavior of functions like
`GNUInstallDirs_get_absolute_install_dir` which make relative install
paths absolute in a more complicated way.
Given all this, I will define a function like the one asked for in
https://gitlab.kitware.com/cmake/cmake/-/issues/19568 (and needed for a
similar use-case).
---
Original message:
Instead of using `COMPILER_RT_INSTALL_PATH` through the CMake for
complier-rt, just use it to define variables for the subdirs which
themselves are used.
This preserves compatibility, but later on we might consider getting rid
of `COMPILER_RT_INSTALL_PATH` and just changing the defaults for the
subdir variables directly.
---
There was a seaming bug where the (non-Apple) per-target libdir was
`${target}` not `lib/${target}`. I suspect that has to do with the docs
on `COMPILER_RT_INSTALL_PATH` saying was the library dir when that's no
longer true, so I just went ahead and fixed it, allowing me to define
fewer and more sensible variables.
That last part should be the only behavior changes; everything else
should be a pure refactoring.
---
I added some documentation of these variables too. In particular, I
wanted to highlight the gotcha where `-DSomeCachePath=...` without the
`:PATH` will lead CMake to make the path absolute. See [1] for
discussion of the problem, and [2] for the brief official documentation
they added as a result.
[1]: https://cmake.org/pipermail/cmake/2015-March/060204.html
[2]: https://cmake.org/cmake/help/latest/manual/cmake.1.html#options
In 38b2dec37e the problem was somewhat
misidentified and so `:STRING` was used, but `:PATH` is better as it
sets the correct type from the get-go.
---
D99484 is the main thrust of the `GnuInstallDirs` work. Once this lands,
it should be feasible to follow both of these up with a simple patch for
compiler-rt analogous to the one for libcxx.
Reviewed By: phosek, #libc_abi, #libunwind
Differential Revision: https://reviews.llvm.org/D105765
This reverts commit 9a9bc76c0e.
That commit broke "ninja install" when building compiler-rt for mingw
targets, building standalone (pointing cmake at the compiler-rt
directory) with cmake 3.16.3 (the one shipped in ubuntu 20.04), with
errors like this:
-- Install configuration: "Release"
CMake Error at cmake_install.cmake:44 (file):
file cannot create directory: /include/sanitizer. Maybe need
administrative privileges.
Call Stack (most recent call first):
/home/martin/code/llvm-mingw/src/llvm-project/compiler-rt/build-i686-sanitizers/cmake_install.cmake:37 (include)
FAILED: include/CMakeFiles/install-compiler-rt-headers
cd /home/martin/code/llvm-mingw/src/llvm-project/compiler-rt/build-i686-sanitizers/include && /usr/bin/cmake -DCMAKE_INSTALL_COMPONENT="compiler-rt-headers" -P /home/martin/code/llvm-mingw/src/llvm-project/compiler-rt/build-i686-sanitizers/cmake_install.cmake
ninja: build stopped: subcommand failed.
Instead of using `COMPILER_RT_INSTALL_PATH` through the CMake for
complier-rt, just use it to define variables for the subdirs which
themselves are used.
This preserves compatibility, but later on we might consider getting rid
of `COMPILER_RT_INSTALL_PATH` and just changing the defaults for the
subdir variables directly.
---
There was a seaming bug where the (non-Apple) per-target libdir was
`${target}` not `lib/${target}`. I suspect that has to do with the docs
on `COMPILER_RT_INSTALL_PATH` saying was the library dir when that's no
longer true, so I just went ahead and fixed it, allowing me to define
fewer and more sensible variables.
That last part should be the only behavior changes; everything else
should be a pure refactoring.
---
D99484 is the main thrust of the `GnuInstallDirs` work. Once this lands,
it should be feasible to follow both of these up with a simple patch for
compiler-rt analogous to the one for libcxx.
Reviewed By: phosek
Differential Revision: https://reviews.llvm.org/D101497
This allows application code checks if origin tracking is on before
printing out traces.
-dfsan-track-origins can be 0,1,2.
The current code only distinguishes 1 and 2 in compile time, but not at runtime.
Made runtime distinguish 1 and 2 too.
Reviewed By: browneee
Differential Revision: https://reviews.llvm.org/D105128
These other platforms are unsupported and untested.
They could be re-added later based on MSan code.
Reviewed By: gbalats, stephan.yichao.zhao
Differential Revision: https://reviews.llvm.org/D104481
These other platforms are unsupported and untested.
They could be re-added later based on MSan code.
Reviewed By: gbalats, stephan.yichao.zhao
Differential Revision: https://reviews.llvm.org/D104481
Complete support for fast8:
- amend shadow size and mapping in runtime
- remove fast16 mode and -dfsan-fast-16-labels flag
- remove legacy mode and make fast8 mode the default
- remove dfsan-fast-8-labels flag
- remove functions in dfsan interface only applicable to legacy
- remove legacy-related instrumentation code and tests
- update documentation.
Reviewed By: stephan.yichao.zhao, browneee
Differential Revision: https://reviews.llvm.org/D103745
dfsan does not use sanitizer allocator as others. In practice,
we let it use glibc's allocator since tcmalloc needs more work
to be working with dfsan well. With glibc, we observe large
memory leakage. This could relate to two things:
1) glibc allocator has limitation: for example, tcmalloc can reduce memory footprint 2x easily
2) glibc may call unmmap directly as an internal system call by using system call number. so DFSan has no way to release shadow spaces for those unmmap.
Using sanitizer allocator addresses the above issues
1) its memory management is close to tcmalloc
2) we can register callback when sanitizer allocator calls unmmap, so dfsan can release shadow spaces correctly.
Our experiment with internal server-based application proved that with the change, in a-few-day run, memory usage leakage is close to what tcmalloc does w/o dfsan.
This change mainly follows MSan's code.
1) define allocator callbacks at dfsan_allocator.h|cpp
2) mark allocator APIs to be discard
3) intercept allocator APIs
4) make dfsan_set_label consistent with MSan's SetShadow when setting 0 labels, define dfsan_release_meta_memory when unmap is called
5) add flags about whether zeroing memory after malloc/free. dfsan works at byte-level, so bit-level oparations can cause reading undefined shadow. See D96842. zeroing memory after malloc helps this. About zeroing after free, reading after free is definitely UB, but if user code does so, it is hard to debug an overtainting caused by this w/o running MSan. So we add the flag to help debugging.
This change will be split to small changes for review. Before that, a question is
"this code shares a lot of with MSan, for example, dfsan_allocator.* and dfsan_new_delete.*.
Does it make sense to unify the code at sanitizer_common? will that introduce some
maintenance issue?"
Reviewed By: morehouse
Differential Revision: https://reviews.llvm.org/D101204
Code patterns like this are common, `#` at the line beginning
(https://google.github.io/styleguide/cppguide.html#Preprocessor_Directives),
one space indentation for if/elif/else directives.
```
#if SANITIZER_LINUX
# if defined(__aarch64__)
# endif
#endif
```
However, currently clang-format wants to reformat the code to
```
#if SANITIZER_LINUX
#if defined(__aarch64__)
#endif
#endif
```
This significantly harms readability in my review. Use `IndentPPDirectives:
AfterHash` to defeat the diagnostic. clang-format will now suggest:
```
#if SANITIZER_LINUX
# if defined(__aarch64__)
# endif
#endif
```
Unfortunately there is no clang-format option using indent with 1 for
just preprocessor directives. However, this is still one step forward
from the current behavior.
Reviewed By: #sanitizers, vitalybuka
Differential Revision: https://reviews.llvm.org/D100238
The first version of origin tracking tracks only memory stores. Although
this is sufficient for understanding correct flows, it is hard to figure
out where an undefined value is read from. To find reading undefined values,
we still have to do a reverse binary search from the last store in the chain
with printing and logging at possible code paths. This is
quite inefficient.
Tracking memory load instructions can help this case. The main issues of
tracking loads are performance and code size overheads.
With tracking only stores, the code size overhead is 38%,
memory overhead is 1x, and cpu overhead is 3x. In practice #load is much
larger than #store, so both code size and cpu overhead increases. The
first blocker is code size overhead: link fails if we inline tracking
loads. The workaround is using external function calls to propagate
metadata. This is also the workaround ASan uses. The cpu overhead
is ~10x. This is a trade off between debuggability and performance,
and will be used only when debugging cases that tracking only stores
is not enough.
Reviewed By: gbalats
Differential Revision: https://reviews.llvm.org/D100967
Andrew Browne