Re: [PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames
From: Kees Cook <hidden>
Date: 2019-06-08 04:00:30
Also in:
amd-gfx, dri-devel, kvm, linux-kselftest, linux-media, linux-mm, linux-rdma, lkml
On Mon, Jun 03, 2019 at 06:55:09PM +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 <redacted>
Reviewed-by: Kees Cook <redacted> -Kees
quoted hunk ↗ jump to hunk
--- 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);-- 2.22.0.rc1.311.g5d7573a151-goog
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