Re: [PATCH v2] kunit/usercopy: Disable testing on !CONFIG_MMU

Rae Moar
2024-06-20T21:13:49Z

On Wed, Jun 19, 2024 at 4:25 PM Kees Cook <kees@kernel.org> wrote:
>
> Since arch_pick_mmap_layout() is an inline for non-MMU systems, disable
> this test there.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202406160505.uBge6TMY-lkp@intel.com/
> Signed-off-by: Kees Cook <kees@kernel.org>

Hello!

This looks good to me. And seems to fix the problem. Thanks for the fix!

Reviewed-by: Rae Moar <rmoar@google.com>

-Rae

> ---
> Resending as v2 with Shuah in To:
> ---
> Cc: Shuah Khan <skhan@linuxfoundation.org>
> Cc: Brendan Higgins <brendan.higgins@linux.dev>
> Cc: David Gow <davidgow@google.com>
> Cc: Rae Moar <rmoar@google.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-kselftest@vger.kernel.org
> Cc: kunit-dev@googlegroups.com
> Cc: linux-hardening@vger.kernel.org
> Cc: linux-mm@kvack.org
> ---
> lib/kunit/user_alloc.c | 4 ++++
> lib/usercopy_kunit.c | 5 +++++
> mm/util.c | 2 ++
> 3 files changed, 11 insertions(+)
>
> diff --git a/lib/kunit/user_alloc.c b/lib/kunit/user_alloc.c
> index 76d3d1345ed7..ae935df09a5e 100644
> --- a/lib/kunit/user_alloc.c
> +++ b/lib/kunit/user_alloc.c
> @@ -30,6 +30,10 @@ static int kunit_attach_mm(void)
> if (current->mm)
> return 0;
>
> + /* arch_pick_mmap_layout() is only sane with MMU systems. */
> + if (!IS_ENABLED(CONFIG_MMU))
> + return -EINVAL;
> +
> mm = mm_alloc();
> if (!mm)
> return -ENOMEM;
> diff --git a/lib/usercopy_kunit.c b/lib/usercopy_kunit.c
> index 45f1e558c464..e819561a540d 100644
> --- a/lib/usercopy_kunit.c
> +++ b/lib/usercopy_kunit.c
> @@ -290,6 +290,11 @@ static int usercopy_test_init(struct kunit *test)
> struct usercopy_test_priv *priv;
> unsigned long user_addr;
>
> + if (!IS_ENABLED(CONFIG_MMU)) {
> + kunit_skip(test, "Userspace allocation testing not available on non-MMU systems");
> + return 0;
> + }
> +
> priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
> test->priv = priv;
> diff --git a/mm/util.c b/mm/util.c
> index df37c47d9374..e70e8e439258 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -484,7 +484,9 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
> clear_bit(MMF_TOPDOWN, &mm->flags);
> }
> #endif
> +#ifdef CONFIG_MMU
> EXPORT_SYMBOL_IF_KUNIT(arch_pick_mmap_layout);
> +#endif
>
> /**
> * __account_locked_vm - account locked pages to an mm's locked_vm
> --
> 2.34.1
>