Bug #22193: Segmentation fault in functions to check MemoryView contiguity with NULL shape and/or strides

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 4.1.0dev (2026-07-13T13:26:16Z origin/master cb2ea293c6) +PRISM [arm64-darwin25]
• Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN

[KitaitiMakoto (真 北市)]

Hello,

I encountered a segmentation fault when calling rb_memory_view_is_row_major_contiguous with a MemoryView whose shape and strides are NULL. For instance, a MemoryView initialized with rb_memory_view_init_as_byte_array function causes this problem. The cause is that the function handles shape and strides as arrays without checking whether they are NULL or not.

Environment

• Ruby commit: cb2ea293c6
• OS: macOS (M2 Mac)

Code to reproduce the problem:

I will send a pull request later for the full patch.

ext/-test-/memory_view/memory_view.c

static VALUE
memory_view_is_row_major_contiguous(VALUE mod, VALUE obj)
{
    rb_memory_view_t view;
    VALUE result;

    if (!rb_memory_view_get(obj, &view, 0)) {
        rb_raise(rb_eArgError, "Unable to get MemoryView");
    }

    result = rb_memory_view_is_row_major_contiguous(&view) ? Qtrue : Qfalse;
    rb_memory_view_release(&view);

    return result;
}

static VALUE
memory_view_is_column_major_contiguous(VALUE mod, VALUE obj)
{
    rb_memory_view_t view;
    VALUE result;

    if (!rb_memory_view_get(obj, &view, 0)) {
        rb_raise(rb_eArgError, "Unable to get MemoryView");
    }

    result = rb_memory_view_is_column_major_contiguous(&view) ? Qtrue : Qfalse;
    rb_memory_view_release(&view);

    return result;
}

// ...

void
Init_memory_view(void)
{

// ...

    rb_define_module_function(mMemoryViewTestUtils, "is_row_major_contiguous", memory_view_is_row_major_contiguous, 1);
    rb_define_module_function(mMemoryViewTestUtils, "is_column_major_contiguous", memory_view_is_column_major_contiguous, 1);

// ...

}

test/ruby/test_memory_view.rb

class TestMemoryView < Test::Unit::TestCase

# ...

  def test_rb_memory_view_is_row_major_contiguous
    es = MemoryViewTestUtils::ExportableString.new("ruby")
    assert_true(MemoryViewTestUtils.is_row_major_contiguous(es))
  end

  def test_rb_memory_view_is_column_major_contiguous
    es = MemoryViewTestUtils::ExportableString.new("ruby")
    assert_true(MemoryViewTestUtils.is_column_major_contiguous(es))
  end

# ...

end

Steps to reproduce the problem:

1. Add code above to the current Ruby (cb2ea293c6)
2. Run make test-all TESTS=test/ruby/test_memory_view.rb
3. Then you can see segmentation fault

Thank you.

[KitaitiMakoto (真 北市)]

I sent a pull request to reproduce and fix the problem: https://github.com/ruby/ruby/pull/17851

[KitaitiMakoto (真 北市)]

• Subject changed from Segmentation fault in functions to MemoryView contiguity with NULL shape and/or strides to Segmentation fault in functions to check MemoryView contiguity with NULL shape and/or strides

[mrkn (Kenta Murata)]

• Status changed from Open to Closed