[compiler-rt] r259007 - [cfi] Fix recovery from out-of-bounds vtable error.

[David Blaikie via llvm-commits]

On Wed, Jan 27, 2016 at 4:37 PM, Evgeniy Stepanov via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: eugenis
> Date: Wed Jan 27 18:37:54 2016
> New Revision: 259007
>
> URL: http://llvm.org/viewvc/llvm-project?rev=259007&view=rev
> Log:
> [cfi] Fix recovery from out-of-bounds vtable error.
>
> Modified:
>     compiler-rt/trunk/lib/cfi/cfi.cc
>     compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
>
> Modified: compiler-rt/trunk/lib/cfi/cfi.cc
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/cfi/cfi.cc?rev=259007&r1=259006&r2=259007&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/lib/cfi/cfi.cc (original)
> +++ compiler-rt/trunk/lib/cfi/cfi.cc Wed Jan 27 18:37:54 2016
> @@ -306,12 +306,14 @@ ALWAYS_INLINE void CfiSlowPathCommon(u64
>      // FIXME: call the ubsan handler if DiagData != nullptr?
>      VReport(1, "CFI: invalid memory region for a check target: %p\n",
> Ptr);
>  #ifdef CFI_ENABLE_DIAG
> -    if (DiagData)
> +    if (DiagData) {
>        __ubsan_handle_cfi_check_fail(
>            reinterpret_cast<__ubsan::CFICheckFailData *>(DiagData),
>            reinterpret_cast<uptr>(Ptr));
> -    else
> +      return;
> +    } else {
>

Drop the else-after-return, and possibly invert to reduce indentation:

  if (!DiagData)
    Trap();
  __ubsaN-handle_...


>        Trap();
> +    }
>  #else
>      Trap();
>  #endif
> @@ -348,7 +350,8 @@ void InitializeFlags() {
>
>    SetVerbosity(common_flags()->verbosity);
>
> -  if (Verbosity()) ReportUnrecognizedFlags();
> +  if (Verbosity())
> +    ReportUnrecognizedFlags();
>
>    if (common_flags()->help) {
>      cfi_parser.PrintFlagDescriptions();
>
> Modified: compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp?rev=259007&r1=259006&r2=259007&view=diff
>
> ==============================================================================
> --- compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
> (original)
> +++ compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp Wed Jan
> 27 18:37:54 2016
> @@ -20,9 +20,13 @@ int main(int argc, char *argv[]) {
>    // enough to handle unaddressable vtables. TODO: fix this.
>    void *empty = calloc(1, 128);
>    uintptr_t v = (uintptr_t)empty + 64;
> -  A *volatile p = new A();
> -  for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + 1); ++q)
> +  char *volatile p = reinterpret_cast<char *>(new A());
> +  for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + sizeof(A));
> ++q)
>      *q = v;
> +
> +  // CHECK: runtime error: control flow integrity check for type 'A'
> failed during cast
> +  A *volatile pa = reinterpret_cast<A *>(p);
> +
>    // CHECK: untime error: control flow integrity check for type 'A'
> failed during virtual call
> -  p->f();
> +  pa->f();
>  }
>
>
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