Crash on ODR between instrumented and non-instrumented libraries about address-sanitizer HOT 4 OPEN

FYI that's what GCC does.

Adding Project:AddressSanitizer as part of GitHub migration.

Hm, I've tried the following (draft) patch:

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp 
b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index f7b7a71..71b65c3 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1338,8 +1338,14 @@ bool 
AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
       SourceLoc = ConstantInt::get(IntptrTy, 0);
     }

+    // Create local alias for NewGlobal to avoid crash on ODR between
+    // instrumented and non-instrumented libraries.
+    // https://code.google.com/p/address-sanitizer/issues/detail?id=398
+    auto *GA = GlobalAlias::create(
+        GlobalValue::InternalLinkage, MD.Name + M.getName(), NewGlobal);
+
     Initializers[i] = ConstantStruct::get(
-        GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
+        GlobalStructTy, ConstantExpr::getPointerCast(GA, IntptrTy),
         ConstantInt::get(IntptrTy, SizeInBytes),
         ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
         ConstantExpr::getPointerCast(Name, IntptrTy),

on this testcase:

$ cat main.c

int f = 4;
int g = 5;
int foo (int *);
int main ()
{
  return foo (&f) - 4;
}

$ cat libfoo.c

int f = 444;
int g = 555;
int foo (int *p)
{
  return *p;
}

and got interesting results. If we force clang to use external (GNU) AS via 
'-no-integrated-as' option, everything works well:

$ clang -no-integrated-as -fsanitize=address libfoo.c -shared -fpic 
-fsanitize=address -o libfoo.so
$ clang main.c -c -o main.o
$ clang -fsanitize=address main.o ./libfoo.so -o main
$ ASAN_OPTIONS=report_globals=3  ./main 
    #0 0x4b49b7 in __asan_register_globals /home/max/src/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:226
    #1 0x7fb518d1fa0d in asan.module_ctor (libfoo.so+0xa0d)
    #2 0x7fb518f31139 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:78
    #3 0x7fb518f31222 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:36
    #4 0x7fb518f31222 in _dl_init /build/buildd/eglibc-2.19/elf/dl-init.c:126
    #5 0x7fb518f22309  (/lib64/ld-linux-x86-64.so.2+0x1309)

=== ID 629145601; 0x7fb518f20100 0x7fb518f20138
==18620==Added Global[0x7fb518f20100]: beg=0x7fb518f20080 size=4/64 name=f 
module=foo.c dyn_init=0
==18620==  location (0x7fb518f1fdf8): name=foo.c[0x7fb518d1fa39], 1 5
==18620==Added Global[0x7fb518f20138]: beg=0x7fb518f200c0 size=4/64 name=g 
module=foo.c dyn_init=0
==18620==  location (0x7fb518f1fe08): name=foo.c[0x7fb518d1fa39], 2 5
==18620==Removed Global[0x7fb518f20100]: beg=0x7fb518f20080 size=4/64 name=f 
module=foo.c dyn_init=0
==18620==  location (0x7fb518f1fdf8): name=foo.c[0x7fb518d1fa39], 1 5
==18620==Removed Global[0x7fb518f20138]: beg=0x7fb518f200c0 size=4/64 name=g 
module=foo.c dyn_init=0
==18620==  location (0x7fb518f1fe08): name=foo.c[0x7fb518d1fa39], 2 5

For f and g, beg is located in libfoo.so and this is fine.

However, when use embedded clang asm, I've got this:

$ clang -fsanitize=address libfoo.c -shared -fpic -fsanitize=address -o 
libfoo.so
$ clang main.c -c -o main.o
$ clang -fsanitize=address main.o ./libfoo.so -o main

$ ASAN_OPTIONS=report_globals=3   ./main 
    #0 0x4b49b7 in __asan_register_globals /home/max/src/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:226
    #1 0x7f09ab41da0d in asan.module_ctor (libfoo.so+0xa0d)
    #2 0x7f09ab62f139 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:78
    #3 0x7f09ab62f222 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:36
    #4 0x7f09ab62f222 in _dl_init /build/buildd/eglibc-2.19/elf/dl-init.c:126
    #5 0x7f09ab620309  (/lib64/ld-linux-x86-64.so.2+0x1309)

=== ID 662700033; 0x7f09ab61e100 0x7f09ab61e138
==18635==Added Global[0x7f09ab61e100]: beg=0x00000070bb10 size=4/64 name=f 
module=foo.c dyn_init=0
==18635==  location (0x7f09ab61ddf8): name=foo.c[0x7f09ab41da39], 1 5
==18635==Added Global[0x7f09ab61e138]: beg=0x00000070bb14 size=4/64 name=g 
module=foo.c dyn_init=0
==18635==  location (0x7f09ab61de08): name=foo.c[0x7f09ab41da39], 2 5
==18635==AddressSanitizer CHECK failed: 
/home/max/src/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:146 
"((AddrIsAlignedByGranularity(g->beg))) != (0)" (0x0, 0x0)
    #0 0x4bca0d in __asan::AsanCheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) /home/max/src/llvm/projects/compiler-rt/lib/asan/asan_rtl.cc:71
    #1 0x4c3b03 in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) /home/max/src/llvm/projects/compiler-rt/lib/sanitizer_common/sanitizer_common.cc:136
    #2 0x4b520b in RegisterGlobal /home/max/src/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:146
    #3 0x4b520b in __asan_register_globals /home/max/src/llvm/projects/compiler-rt/lib/asan/asan_globals.cc:230
    #4 0x7f09ab41da0d in asan.module_ctor (libfoo.so+0xa0d)
    #5 0x7f09ab62f139 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:78
    #6 0x7f09ab62f222 in call_init /build/buildd/eglibc-2.19/elf/dl-init.c:36
    #7 0x7f09ab62f222 in _dl_init /build/buildd/eglibc-2.19/elf/dl-init.c:126
    #8 0x7f09ab620309  (/lib64/ld-linux-x86-64.so.2+0x1309)

Here, beg for f and g beg=0x00000070bb**, that is located in main. So, for 
embedded asm local aliases didn't work. I wonder if this is an assembler bug? 
Or maybe there is another way to create local alias that would work with both 
external an embedded as?

The patch looks good in principle, but it has to work with intergrated-as.
Could you try reproducing the difference in the assembler behavior and file a 
bug with llvm?