Re: [PATCH v13 18/20] tee/optee, arm64: untag user pointers in check_mem_type

Andrey Konovalov
2019-04-01T16:31:02Z

On Fri, Mar 22, 2019 at 5:22 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Wed, Mar 20, 2019 at 03:51:32PM +0100, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > check_mem_type() uses provided user pointers for vma lookups (via
> > __check_mem_type()), which can only by done with untagged pointers.
> >
> > Untag user pointers in this function.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> > drivers/tee/optee/call.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
> > index a5afbe6dee68..e3be20264092 100644
> > --- a/drivers/tee/optee/call.c
> > +++ b/drivers/tee/optee/call.c
> > @@ -563,6 +563,7 @@ static int check_mem_type(unsigned long start, size_t num_pages)
> > int rc;
> >
> > down_read(&mm->mmap_sem);
> > + start = untagged_addr(start);
> > rc = __check_mem_type(find_vma(mm, start),
> > start + num_pages * PAGE_SIZE);
> > up_read(&mm->mmap_sem);
>
> I guess we could just untag this in tee_shm_register(). The tag is not
> relevant to a TEE implementation (firmware) anyway.

Will do in v14, thanks!

>
> --
> Catalin