[Linaro-mm-sig] Re: [PATCH v2 14/16] kasan: Remove ksize()-related tests

On Sat, Sep 24, 2022 at 10:15:18AM +0200, Dmitry Vyukov wrote:

On Fri, 23 Sept 2022 at 22:28, Kees Cook keescook@chromium.org wrote:

...

In preparation for no longer unpoisoning in ksize(), remove the behavioral self-tests for ksize().

[...] -/* Check that ksize() makes the whole object accessible. */ -static void ksize_unpoisons_memory(struct kunit *test) -{

•   char *ptr;
  

•   size_t size = 123, real_size;
  

•   ptr = kmalloc(size, GFP_KERNEL);
  

•   KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
  

•   real_size = ksize(ptr);
  

•   OPTIMIZER_HIDE_VAR(ptr);
  

•   /* This access shouldn't trigger a KASAN report. */
  

•   ptr[size] = 'x';
  

I would rather keep the tests and update to the new behavior. We had bugs in ksize, we need test coverage. I assume ptr[size] access must now produce an error even after ksize.

Good point on all these! I'll respin.