[PATCH] D16824: [cfi] Safe handling of unaddressable vtable pointers (compiler-rt).

[Evgeniy Stepanov via llvm-commits]

eugenis added inline comments.

================
Comment at: test/cfi/cross-dso/target_out_of_bounds.cpp:41
@@ +40,3 @@
+    for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + sizeof(A)); ++q)
+      *q = v;
+    // CHECK-ZERO: runtime error: control flow integrity check for type 'A' failed during cast
----------------
pcc wrote:
> Why not just `memset(p, 0, sizeof(A));`?
Because that would test a different thing.


================
Comment at: test/cfi/cross-dso/target_out_of_bounds.cpp:51-55
@@ +50,7 @@
+    // typeinfo pointer.
+    void *empty = calloc(1, 128);
+    memset(empty, 0xFE, 128);
+    uintptr_t v = (uintptr_t)empty + 64;
+    for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + sizeof(A)); ++q)
+      *q = v;
+    // CHECK-TYPEINFO: runtime error: control flow integrity check for type 'A' failed during cast
----------------
pcc wrote:
> Likewise `memset(p, 0xFE, sizeof(A));`
That, again, would be quite different.
This code is testing an invalid TypeInfo pointer, not an invalid vptr.



Repository:
  rL LLVM

http://reviews.llvm.org/D16824