Re: [PATCH v8 3/8] arm64: untag user addresses in access_ok and __uaccess_mask_ptr

On Thu, Nov 08, 2018 at 03:36:10PM +0100, Andrey Konovalov wrote:

copy_from_user (and a few other similar functions) are used to copy data from user memory into the kernel memory or vice versa. Since a user can provided a tagged pointer to one of the syscalls that use copy_from_user, we need to correctly handle such pointers.

Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr, before performing access validity checks.

Signed-off-by: Andrey Konovalov andreyknvl@google.com

Reviewed-by: Catalin Marinas catalin.marinas@arm.com