hanchenye-llvm-project/compiler-rt/test/cfi/overwrite.cpp

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// RUN: %clangxx_cfi -o %t %s
// RUN: not --crash %t 2>&1 | FileCheck --check-prefix=CFI %s
// RUN: %clangxx -o %t %s
// RUN: %t 2>&1 | FileCheck --check-prefix=NCFI %s
// Tests that the CFI mechanism crashes the program when a virtual table is
// replaced with a compatible table of function pointers that does not belong to
// any class, by manually overwriting the virtual table of an object and
// attempting to make a call through it.
#include <stdio.h>
struct A {
virtual void f();
};
void A::f() {}
void foo() {
fprintf(stderr, "foo\n");
}
void *fake_vtable[] = { (void *)&foo };
int main() {
A *a = new A;
*((void **)a) = fake_vtable; // UB here
// CFI: 1
// NCFI: 1
fprintf(stderr, "1\n");
// CFI-NOT: foo
// NCFI: foo
a->f();
// CFI-NOT: 2
// NCFI: 2
fprintf(stderr, "2\n");
}