Index: compiler-rt/lib/asan/asan_globals.cc =================================================================== --- compiler-rt/lib/asan/asan_globals.cc +++ compiler-rt/lib/asan/asan_globals.cc @@ -384,6 +384,10 @@ } RegisterGlobal(&globals[i]); } + + // Poison the metadata. It should not be accessible to user code. + PoisonShadow(reinterpret_cast(globals), n * sizeof(__asan_global), + kAsanGlobalRedzoneMagic); } // Unregister an array of globals. Index: compiler-rt/test/asan/TestCases/Helpers/underflow.cc =================================================================== --- /dev/null +++ compiler-rt/test/asan/TestCases/Helpers/underflow.cc @@ -0,0 +1 @@ +int YYY[3]={1,2,3}; Index: compiler-rt/test/asan/TestCases/global-underflow.cc =================================================================== --- /dev/null +++ compiler-rt/test/asan/TestCases/global-underflow.cc @@ -0,0 +1,17 @@ +// RUN: %clangxx_asan -O0 %s %p/Helpers/underflow.cc -o %t && not %run %t 2>&1 | FileCheck %s +// RUN: %clangxx_asan -O1 %s %p/Helpers/underflow.cc -o %t && not %run %t 2>&1 | FileCheck %s +// RUN: %clangxx_asan -O2 %s %p/Helpers/underflow.cc -o %t && not %run %t 2>&1 | FileCheck %s +// RUN: %clangxx_asan -O3 %s %p/Helpers/underflow.cc -o %t && not %run %t 2>&1 | FileCheck %s + +int XXX[2] = {2, 3}; +extern int YYY[]; +#include +int main(int argc, char **argv) { + memset(XXX, 0, 2*sizeof(int)); + // CHECK: {{READ of size 4 at 0x.* thread T0}} + // CHECK: {{ #0 0x.* in main .*global-underflow.cc:}}[[@LINE+3]] + // CHECK: {{0x.* is located 4 bytes to the left of global variable}} + // CHECK: {{.*YYY.* of size 12}} + int res = YYY[-1]; + return res; +}