overwrite.cpp
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// RUN: %clangxx_cfi -o %t1 %s
// RUN: %expect_crash_unless_devirt %run %t1 2>&1 | FileCheck --check-prefix=CFI %s
// RUN: %clangxx_cfi -DB32 -o %t2 %s
// RUN: %expect_crash %run %t2 2>&1 | FileCheck --check-prefix=CFI %s
// RUN: %clangxx_cfi -DB64 -o %t3 %s
// RUN: %expect_crash %run %t3 2>&1 | FileCheck --check-prefix=CFI %s
// RUN: %clangxx_cfi -DBM -o %t4 %s
// RUN: %expect_crash %run %t4 2>&1 | FileCheck --check-prefix=CFI %s
// RUN: %clangxx -o %t5 %s
// RUN: %run %t5 2>&1 | FileCheck --check-prefix=NCFI %s
// RUN: %clangxx_cfi_diag -o %t6 %s
// RUN: %run %t6 2>&1 | FileCheck --check-prefix=CFI-DIAG %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.
// REQUIRES: cxxabi
#include <stdio.h>
#include "utils.h"
struct A {
virtual void f();
};
void A::f() {}
void foo() {
fprintf(stderr, "foo\n");
}
void *fake_vtable[] = { 0, 0, (void *)&foo };
int main() {
create_derivers<A>();
A *a = new A;
*((void **)a) = fake_vtable + 2; // UB here
break_optimization(a);
// CFI: 1
// NCFI: 1
fprintf(stderr, "1\n");
// CFI-NOT: foo
// NCFI: foo
// CFI-DIAG: runtime error: control flow integrity check for type 'A' failed during virtual call
// CFI-DIAG-NEXT: note: invalid vtable
a->f();
// We don't check for the absence of a 2 here because under devirtualization
// our virtual call may be devirtualized and we will proceed with execution
// rather than crashing.
// NCFI: {{^2$}}
fprintf(stderr, "2\n");
}