[tsan] Fix running check-ubsan with COMPILER_RT_DEBUG=ON #83890
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Created using spr 1.3.6-beta.1
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: Alexander Richardson (arichardson) ChangesTestCases/Misc/Linux/sigaction.cpp fails because dlsym() may call malloc Fix this by marking the thread local variable accesses inside the This is probably a better alternative to #83886. This fixes a different crash but is related to #46204. Backtrace: Full diff: https://github.com/llvm/llvm-project/pull/83890.diff 1 Files Affected:
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp
index 40fe56661250e5..41d6d2a7782347 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp
@@ -212,7 +212,7 @@ struct InternalDeadlockDetector {
return initialized > 0;
}
};
-
+__attribute__((tls_model("initial-exec")))
static THREADLOCAL InternalDeadlockDetector deadlock_detector;
void CheckedMutex::LockImpl(uptr pc) { deadlock_detector.Lock(type_, pc); }
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✅ With the latest revision this PR passed the C/C++ code formatter. |
Created using spr 1.3.6-beta.1
arichardson
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Mar 7, 2024
TestCases/Misc/Linux/sigaction.cpp fails because dlsym() may call malloc on failure. And then the wrapped malloc appears to access thread local storage using global dynamic accesses, thus calling ___interceptor___tls_get_addr, before REAL(__tls_get_addr) has been set, so we get a crash inside ___interceptor___tls_get_addr. For example, this can happen when looking up __isoc23_scanf which might not exist in some libcs. Fix this by marking the thread local variable accessed inside the debug checks as "initial-exec", which does not require __tls_get_addr. This is probably a better alternative to llvm#83886. This fixes a different crash but is related to llvm#46204. Backtrace: ``` #0 0x0000000000000000 in ?? () llvm#1 0x00007ffff6a9d89e in ___interceptor___tls_get_addr (arg=0x7ffff6b27be8) at /path/to/llvm/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:2759 llvm#2 0x00007ffff6a46bc6 in __sanitizer::CheckedMutex::LockImpl (this=0x7ffff6b27be8, pc=140737331846066) at /path/to/llvm/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp:218 llvm#3 0x00007ffff6a448b2 in __sanitizer::CheckedMutex::Lock (this=0x7ffff6b27be8, this@entry=0x730000000580) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_mutex.h:129 llvm#4 __sanitizer::Mutex::Lock (this=0x7ffff6b27be8, this@entry=0x730000000580) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_mutex.h:167 llvm#5 0x00007ffff6abdbb2 in __sanitizer::GenericScopedLock<__sanitizer::Mutex>::GenericScopedLock (mu=0x730000000580, this=<optimized out>) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_mutex.h:383 llvm#6 __sanitizer::SizeClassAllocator64<__tsan::AP64>::GetFromAllocator (this=0x7ffff7487dc0 <__tsan::allocator_placeholder>, stat=stat@entry=0x7ffff570db68, class_id=11, chunks=chunks@entry=0x7ffff5702cc8, n_chunks=n_chunks@entry=128) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_allocator_primary64.h:207 llvm#7 0x00007ffff6abdaa0 in __sanitizer::SizeClassAllocator64LocalCache<__sanitizer::SizeClassAllocator64<__tsan::AP64> >::Refill (this=<optimized out>, c=c@entry=0x7ffff5702cb8, allocator=<optimized out>, class_id=<optimized out>) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_allocator_local_cache.h:103 llvm#8 0x00007ffff6abd731 in __sanitizer::SizeClassAllocator64LocalCache<__sanitizer::SizeClassAllocator64<__tsan::AP64> >::Allocate (this=0x7ffff6b27be8, allocator=0x7ffff5702cc8, class_id=140737311157448) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_allocator_local_cache.h:39 llvm#9 0x00007ffff6abc397 in __sanitizer::CombinedAllocator<__sanitizer::SizeClassAllocator64<__tsan::AP64>, __sanitizer::LargeMmapAllocatorPtrArrayDynamic>::Allocate (this=0x7ffff5702cc8, cache=0x7ffff6b27be8, size=<optimized out>, size@entry=175, alignment=alignment@entry=16) at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_allocator_combined.h:69 llvm#10 0x00007ffff6abaa6a in __tsan::user_alloc_internal (thr=0x7ffff7ebd980, pc=140737331499943, sz=sz@entry=175, align=align@entry=16, signal=true) at /path/to/llvm/compiler-rt/lib/tsan/rtl/tsan_mman.cpp:198 llvm#11 0x00007ffff6abb0d1 in __tsan::user_alloc (thr=0x7ffff6b27be8, pc=140737331846066, sz=11, sz@entry=175) at /path/to/llvm/compiler-rt/lib/tsan/rtl/tsan_mman.cpp:223 llvm#12 0x00007ffff6a693b5 in ___interceptor_malloc (size=175) at /path/to/llvm/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:666 llvm#13 0x00007ffff7fce7f2 in malloc (size=175) at ../include/rtld-malloc.h:56 llvm#14 __GI__dl_exception_create_format (exception=exception@entry=0x7fffffffd0d0, objname=0x7ffff7fc3550 "/path/to/llvm/compiler-rt/cmake-build-all-sanitizers/lib/linux/libclang_rt.tsan-x86_64.so", fmt=fmt@entry=0x7ffff7ff2db9 "undefined symbol: %s%s%s") at ./elf/dl-exception.c:157 llvm#15 0x00007ffff7fd50e8 in _dl_lookup_symbol_x (undef_name=0x7ffff6af868b "__isoc23_scanf", undef_map=<optimized out>, ref=0x7fffffffd148, symbol_scope=<optimized out>, version=<optimized out>, type_class=0, flags=2, skip_map=0x7ffff7fc35e0) at ./elf/dl-lookup.c:793 --Type <RET> for more, q to quit, c to continue without paging-- llvm#16 0x00007ffff656d6ed in do_sym (handle=<optimized out>, name=0x7ffff6af868b "__isoc23_scanf", who=0x7ffff6a3bb84 <__interception::InterceptFunction(char const*, unsigned long*, unsigned long, unsigned long)+36>, vers=vers@entry=0x0, flags=flags@entry=2) at ./elf/dl-sym.c:146 llvm#17 0x00007ffff656d9dd in _dl_sym (handle=<optimized out>, name=<optimized out>, who=<optimized out>) at ./elf/dl-sym.c:195 llvm#18 0x00007ffff64a2854 in dlsym_doit (a=a@entry=0x7fffffffd3b0) at ./dlfcn/dlsym.c:40 llvm#19 0x00007ffff7fcc489 in __GI__dl_catch_exception (exception=exception@entry=0x7fffffffd310, operate=0x7ffff64a2840 <dlsym_doit>, args=0x7fffffffd3b0) at ./elf/dl-catch.c:237 llvm#20 0x00007ffff7fcc5af in _dl_catch_error (objname=0x7fffffffd368, errstring=0x7fffffffd370, mallocedp=0x7fffffffd367, operate=<optimized out>, args=<optimized out>) at ./elf/dl-catch.c:256 llvm#21 0x00007ffff64a2257 in _dlerror_run (operate=operate@entry=0x7ffff64a2840 <dlsym_doit>, args=args@entry=0x7fffffffd3b0) at ./dlfcn/dlerror.c:138 llvm#22 0x00007ffff64a28e5 in dlsym_implementation (dl_caller=<optimized out>, name=<optimized out>, handle=<optimized out>) at ./dlfcn/dlsym.c:54 llvm#23 ___dlsym (handle=<optimized out>, name=<optimized out>) at ./dlfcn/dlsym.c:68 llvm#24 0x00007ffff6a3bb84 in __interception::GetFuncAddr (name=0x7ffff6af868b "__isoc23_scanf", trampoline=140737311157448) at /path/to/llvm/compiler-rt/lib/interception/interception_linux.cpp:42 llvm#25 __interception::InterceptFunction (name=0x7ffff6af868b "__isoc23_scanf", ptr_to_real=0x7ffff74850e8 <__interception::real___isoc23_scanf>, func=11, trampoline=140737311157448) at /path/to/llvm/compiler-rt/lib/interception/interception_linux.cpp:61 llvm#26 0x00007ffff6a9f2d9 in InitializeCommonInterceptors () at /path/to/llvm/compiler-rt/lib/tsan/rtl/../../sanitizer_common/sanitizer_common_interceptors.inc:10315 ``` Pull Request: llvm#83890
vitalybuka
approved these changes
Mar 7, 2024
MaskRay
approved these changes
Mar 8, 2024
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I prefer this to the alternative that changes the interceptor order.
tls_model("initial-exec") will make the code not suitable when the runtime is dlopened, which can be ignored for this use case. In addition, this is for COMPILER_RT_DEBUG=ON, a debugging feature.
MaskRay
reviewed
Mar 8, 2024
Created using spr 1.3.6-beta.1
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This can be useful because dlsym() may call malloc on failure which could result in other interposed functions being called that could eventually make use of TLS. While the crash that I experienced originally has been fixed differently (by not using global-dynamic TLS accesses in the mutex deadlock detector, see #83890), moving this interception earlier is still a good since it makes the code a bit more robust against initialization order problems. Reviewed By: MaskRay, vitalybuka Pull Request: #83886
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TestCases/Misc/Linux/sigaction.cpp fails because dlsym() may call malloc
on failure. And then the wrapped malloc appears to access thread local
storage using global dynamic accesses, thus calling
___interceptor___tls_get_addr, before REAL(__tls_get_addr) has
been set, so we get a crash inside ___interceptor___tls_get_addr. For
example, this can happen when looking up __isoc23_scanf which might not
exist in some libcs.
Fix this by marking the thread local variable accessed inside the
debug checks as "initial-exec", which does not require __tls_get_addr.
This is probably a better alternative to #83886.
This fixes a different crash but is related to #46204.
Backtrace: