[compiler-rt] r202266 - [asan] remove UB (comparison of two unrelated pointers) from a test

[David Blaikie]

On Wed, Feb 26, 2014 at 5:53 AM, Kostya Serebryany <kcc at google.com> wrote:
> Author: kcc
> Date: Wed Feb 26 07:53:23 2014
> New Revision: 202266
>
> URL: http://llvm.org/viewvc/llvm-project?rev=202266&view=rev
> Log:
> [asan] remove UB (comparison of two unrelated pointers) from a test

I assume you're aware of this (& chose the below fix as the better one
anyway - which is totally fine) but you can have a well-defined
comparison of unrelated pointers using std::less, if you happen to
need/want/prefer that.

>
> Modified:
>     compiler-rt/trunk/lib/asan/tests/asan_mem_test.cc
>
> Modified: compiler-rt/trunk/lib/asan/tests/asan_mem_test.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/tests/asan_mem_test.cc?rev=202266&r1=202265&r2=202266&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/asan/tests/asan_mem_test.cc (original)
> +++ compiler-rt/trunk/lib/asan/tests/asan_mem_test.cc Wed Feb 26 07:53:23 2014
> @@ -76,17 +76,17 @@ TEST(AddressSanitizer, MemSetOOBTest) {
>  // Strictly speaking we are not guaranteed to find such two pointers,
>  // but given the structure of asan's allocator we will.
>  static bool AllocateTwoAdjacentArrays(char **x1, char **x2, size_t size) {
> -  vector<char *> v;
> +  vector<uintptr_t> v;
>    bool res = false;
>    for (size_t i = 0; i < 1000U && !res; i++) {
> -    v.push_back(new char[size]);
> +    v.push_back(reinterpret_cast<uintptr_t>(new char[size]));
>      if (i == 0) continue;
>      sort(v.begin(), v.end());
>      for (size_t j = 1; j < v.size(); j++) {
>        assert(v[j] > v[j-1]);
>        if ((size_t)(v[j] - v[j-1]) < size * 2) {
> -        *x2 = v[j];
> -        *x1 = v[j-1];
> +        *x2 = reinterpret_cast<char*>(v[j]);
> +        *x1 = reinterpret_cast<char*>(v[j-1]);
>          res = true;
>          break;
>        }
> @@ -94,9 +94,10 @@ static bool AllocateTwoAdjacentArrays(ch
>    }
>
>    for (size_t i = 0; i < v.size(); i++) {
> -    if (res && v[i] == *x1) continue;
> -    if (res && v[i] == *x2) continue;
> -    delete [] v[i];
> +    char *p = reinterpret_cast<char *>(v[i]);
> +    if (res && p == *x1) continue;
> +    if (res && p == *x2) continue;
> +    delete [] p;
>    }
>    return res;
>  }
>
>
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