On Tue, Apr 30, 2019 at 03:25:04PM +0200, 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. > > get_vaddr_frames uses provided user pointers for vma lookups, which can > only by done with untagged pointers. Instead of locating and changing > all callers of this function, perform untagging in it. > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > --- > mm/frame_vector.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > index c64dca6e27c2..c431ca81dad5 100644 > --- a/mm/frame_vector.c > +++ b/mm/frame_vector.c > @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) > nr_frames = vec->nr_allocated; > > + start = untagged_addr(start); > + > down_read(&mm->mmap_sem); > locked = 1; > vma = find_vma_intersection(mm, start, start + 1); Is this some buffer that the user may have malloc'ed? I got lost when trying to track down the provenience of this buffer. -- Catalin
