compiler-rt/test/cfi/overwrite.cpp

   1 // RUN: %clangxx_cfi -o %t1 %s
   2 // RUN: %expect_crash_unless_devirt %run %t1 2>&1 | FileCheck --check-prefix=CFI %s
   3
   4 // RUN: %clangxx_cfi -DB32 -o %t2 %s
   5 // RUN: %expect_crash %run %t2 2>&1 | FileCheck --check-prefix=CFI %s
   6
   7 // RUN: %clangxx_cfi -DB64 -o %t3 %s
   8 // RUN: %expect_crash %run %t3 2>&1 | FileCheck --check-prefix=CFI %s
   9
  10 // RUN: %clangxx_cfi -DBM -o %t4 %s
  11 // RUN: %expect_crash %run %t4 2>&1 | FileCheck --check-prefix=CFI %s
  12
  13 // RUN: %clangxx -o %t5 %s
  14 // RUN: %run %t5 2>&1 | FileCheck --check-prefix=NCFI %s
  15
  16 // RUN: %clangxx_cfi_diag -o %t6 %s
  17 // RUN: %run %t6 2>&1 | FileCheck --check-prefix=CFI-DIAG %s
  18
  19 // Tests that the CFI mechanism crashes the program when a virtual table is
  20 // replaced with a compatible table of function pointers that does not belong to
  21 // any class, by manually overwriting the virtual table of an object and
  22 // attempting to make a call through it.
  23
  24 // REQUIRES: cxxabi
  25
  26 #include <stdio.h>
  27 #include "utils.h"
  28
  29 struct A {
  30   virtual void f();
  31 };
  32
  33 void A::f() {}
  34
  35 void foo() {
  36   fprintf(stderr, "foo\n");
  37 }
  38
  39 void *fake_vtable[] = { 0, 0, (void *)&foo };
  40
  41 int main() {
  42   create_derivers<A>();
  43
  44   A *a = new A;
  45   *((void **)a) = fake_vtable + 2; // UB here
  46   break_optimization(a);
  47
  48   // CFI: 1
  49   // NCFI: 1
  50   fprintf(stderr, "1\n");
  51
  52   // CFI-NOT: foo
  53   // NCFI: foo
  54   // CFI-DIAG: runtime error: control flow integrity check for type 'A' failed during virtual call
  55   // CFI-DIAG-NEXT: note: invalid vtable
  56   a->f();
  57
  58   // We don't check for the absence of a 2 here because under devirtualization
  59   // our virtual call may be devirtualized and we will proceed with execution
  60   // rather than crashing.
  61
  62   // NCFI: {{^2$}}
  63   fprintf(stderr, "2\n");
  64 }