| tag | f0d8aa26c2f5cc8a6ad85b88a48e7a6233bb33aa | |
|---|---|---|
| tagger | Tobias Hieta <tobias@hieta.se> | Tue Oct 17 08:23:49 2023 +0200 |
| object | 888437e1b60011b8a375dd30928ec925b448da57 |
LLVM 17.0.3 Release
| commit | 888437e1b60011b8a375dd30928ec925b448da57 | [log] [tgz] |
|---|---|---|
| author | Fangrui Song <i@maskray.me> | Wed Oct 11 09:23:56 2023 -0700 |
| committer | Tobias Hieta <tobias@hieta.se> | Tue Oct 17 08:20:52 2023 +0200 |
| tree | a734880e7415871173881580fb28dd07f461a133 | |
| parent | 2e00f4ca4e91b02ff8e6e2d3f8e5bdd544054cb2 [diff] |
[asan] Ensure __asan_register_elf_globals is called in COMDAT asan.module_ctor (#67745)
On ELF platforms, when there is no global variable and the unique module ID is
non-empty, COMDAT asan.module_ctor is created with no
`__asan_register_elf_globals` calls. If this COMDAT is the prevailing copy
selected by the linker, the linkage unit will have no
`__asan_register_elf_globals` call: the redzone will not be poisoned and ODR
violation checker will not work (#67677).
This behavior is benign for -fno-sanitize-address-globals-dead-stripping because
asan.module_ctor functions that call `__asan_register_globals`
(`InstrumentGlobalsWithMetadataArray`) do not use COMDAT.
To fix #67677:
* Use COMDAT for -fsanitize-address-globals-dead-stripping on ELF platforms.
* Call `__asan_register_elf_globals` even if there is no global variable.
* If the unique module ID is empty, don't call SetComdatForGlobalMetadata:
placing `@.str` in a COMDAT would incorrectly discard internal COMDAT `@.str`
in other compile units.
Alternatively, when there is no global variable, asan.module_ctor is not COMDAT
and does not call `__asan_register_elf_globals`. However, the asan.module_ctor
function cannot be eliminated by the linker.
Tested the following script. Only ELF -fsanitize-address-globals-dead-stripping has changed behaviors.
```
echo > a.cc # no global variable, empty uniqueModuleId
echo 'void f() {}' > b.cc # with global variable, with uniqueModuleId
echo 'int g;' > c.cc # with global variable
for t in x86_64-linux-gnu arm64-apple-macosx x86_64-windows-msvc; do
for gc in -f{,no-}sanitize-address-globals-dead-stripping; do
for f in a.cc b.cc c.cc; do
echo /tmp/Rel/bin/clang -S --target=$t -fsanitize=address $gc $f -o -
/tmp/Rel/bin/clang -S --target=$t -fsanitize=address $gc $f -o - | sed -n '/asan.module_ctor/,/ret/p'
done
done
done
```
---
Identical to commit 16eed8c906875e748c3cb610f3dc4b875f3882aa.
6420d3301cd4f0793adcf11f59e8398db73737d8 is an incorrect revert for genuine
purely internal issues.
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