Re: [PATCH v25 29/30] mm: Update arch_validate_flags() to include vma anonymous

On Thu, Apr 15, 2021 at 03:14:18PM -0700, Yu-cheng Yu wrote:

When newer VM flags are being created, such as VM_MTE, it becomes necessary
for mmap/mprotect to verify if certain flags are being applied to an
anonymous VMA.

To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
is specified [1], and then using the flag in arch_validate_flags().

Another approach is passing vma_is_anonymous() to arch_validate_flags().
To prepare the introduction of PROT_SHSTK, which creates a shadow stack
mapping and can only be applied to an anonymous VMA, update arch_validate_
flags() to include anonymous VMA information.

I would rather pass down whole vma. Who knows what else
arch_validate_flags() would need to know about the VMA tomorrow:

	arch_validate_flags(vma, newflags);

should do the trick.

-- 
 Kirill A. Shutemov