Segmentation fault when logistic_map_10_pelemaey(1..10)

[zacky1972]

Describe the bug A clear and concise description of what the bug is.

To Reproduce Steps to reproduce the behavior:

1. Use Pelemay in the source code

defmodule LogisticMap do
  import Pelemay
  defpelemay do
    def logistic_map_10_pelemay(list) do
      list
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
      |> Enum.map(&rem(22 * &1 * (&1 + 1), 6_700_417))
    end
  end
end

2. Run in the command iex -S mix and the following execution:

iex> LogisticMap.logistic_map_10_pelemay(1..10)

3. See a segmantation fault.

Expected behavior A clear and concise description of what you expected to happen.

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

CpuInfo.all_profile
%{
  compiler: %{
    apple_clang: [
      %{
        bin: "/usr/bin/clang",
        type: :apple_clang,
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      }
    ],
    "apple_clang++": [
      %{
        bin: "/usr/bin/clang++",
        type: :"apple_clang++",
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      }
    ],
    cc_env: [],
    cflags_env: "",
    clang: [
      %{
        bin: "/usr/bin/clang",
        type: :apple_clang,
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      }
    ],
    "clang++": [
      %{
        bin: "/usr/bin/clang++",
        type: :"apple_clang++",
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      }
    ],
    cxx_env: [],
    cxxflags_env: "",
    "g++": [
      %{ 
        bin: "/usr/bin/g++",
        type: :"apple_clang++",
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      },
      %{
        bin: "/usr/local/bin/g++-5",
        type: :"g++",
        version: "5.5.0",
        versions: "g++-5 (Homebrew GCC 5.5.0_6) 5.5.0"
      }
    ],
    gcc: [
      %{
        bin: "/usr/bin/gcc",
        type: :apple_clang,
        version: "12.0.0",
        versions: "Apple clang version 12.0.0 (clang-1200.0.32.28)"
      },
      %{
        bin: "/usr/local/bin/gcc-5",
        type: :gcc,
        version: "5.5.0",
        versions: "gcc-5 (Homebrew GCC 5.5.0_6) 5.5.0"
      }
    ],
    ldflags_env: ""
  },
  cpu: %{
    cpu_model: "6-Core Intel Core i5",
    cpu_models: ["6-Core Intel Core i5"],
    cpu_type: "x86_64",
    hyper_threading: :disabled,
    num_of_cores_of_a_processor: 6,
    num_of_ecores: 0,
    num_of_pcores: 0,
    num_of_processors: 1,
    num_of_threads_of_a_processor: 6,
    os_type: :macos,
    total_num_of_cores: 6,
    total_num_of_threads: 6
  },
  cuda: %{cuda: false},
  elixir: %{version: "1.11.3"},
  erlang: %{otp_version: 23},
  kernel: %{
    kernel_release: "19.6.0",
    kernel_version: "Darwin 19.6.0",
    system_version: "macOS 10.15.7 (19H114)"
  },
  metal: %{metal: true}
}

Additional context

This error occurs even if v0.0.14.

[zacky1972]

If run the following on iex, such a segmentation fault doesn't occur:

iex> LogisticMap.logistic_map_10_pelemay(1..16)

[christianjgreen]

Hey there! I was looking into this a bit and believe there is not enough space being allocated for the internal vector holding the list.

Valgrind revealed the following:

==30428== 1 errors in context 1 of 35:
==30428== Thread 6 2_scheduler:
==30428== Invalid read of size 8
==30428==    at 0x4B3245F0: map_elem1_plus_1_mult_1_mult_elem1_mod_6700413_kernel_i64 (map_elem1_plus_1_mult_1_mult_elem1_mod_6700413_kernel.c:25)
==30428==    by 0x4B323DAF: map_elem1_plus_1_mult_1_mult_elem1_mod_6700413_yielding_nif (libnifelixirlogisticmap.c:597)
==30428==    by 0x3909A0: execute_nif (erl_nif.c:3117)
==30428==    by 0x188CA8: process_main (beam_cold.h:184)
==30428==    by 0x1A53EE: sched_thread_func (erl_process.c:8486)
==30428==    by 0x4B532C: thr_wrapper (ethread.c:122)
==30428==    by 0x49E6608: start_thread (pthread_create.c:477)
==30428==    by 0x4B22292: clone (clone.S:95)
==30428==  Address 0x49044118 is 8 bytes after a block of size 64 alloc'd
==30428==    at 0x483B7F3: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==30428==    by 0x3C887D: erts_sys_alloc (sys.c:871)
==30428==    by 0x388BB4: erts_alloc_fnf (erl_alloc.h:294)
==30428==    by 0x38AD65: enif_alloc (erl_nif.c:529)
==30428==    by 0x4B325649: enif_get_int64_vec_from_list (basic.c:80)
==30428==    by 0x4B32396E: map_elem1_plus_1_mult_1_mult_elem1_mod_6700413_nif (libnifelixirlogisticmap.c:536)
==30428==    by 0x188CA8: process_main (beam_cold.h:184)
==30428==    by 0x1A53EE: sched_thread_func (erl_process.c:8486)
==30428==    by 0x4B532C: thr_wrapper (ethread.c:122)
==30428==    by 0x49E6608: start_thread (pthread_create.c:477)
==30428==    by 0x4B22292: clone (clone.S:95)

In basic.c:80 the line is

size_t nn = CACHE_LINE_SIZE;
ErlNifSInt64 *t = (ErlNifSInt64 *)enif_alloc(nn);

Since t is being used as an array below (&t[i++]) is the sizeof() function missing during the allocation?

I was playing around with something like this that seemed to clear the mem leaks. Where length is derived from enif_get_list_lengh since *vec_l might be NULL.

size_t nn = CACHE_LINE_SIZE;
ErlNifSInt64 *t = (ErlNifSInt64 *)enif_alloc(sizeof(ErlNifSInt64) * length);

I'd like to get your thoughts before moving forward with a PR :)