From cd5297b0855f17c8b4e3ef1d20c6a3656209c7b3 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 1 Mar 2021 10:52:53 +0100 Subject: drm/etnaviv: Use FOLL_FORCE for userptr Nothing checks userptr.ro except this call to pup_fast, which means there's nothing actually preventing userspace from writing to this. Which means you can just read-only mmap any file you want, userptr it and then write to it with the gpu. Not good. The right way to handle this is FOLL_WRITE | FOLL_FORCE, which will break any COW mappings and update tracking for MAY_WRITE mappings so there's no exploit and the vm isn't confused about what's going on. For any legit use case there's no difference from what userspace can observe and do. Reviewed-by: Lucas Stach Cc: stable@vger.kernel.org Cc: John Hubbard Signed-off-by: Daniel Vetter Cc: Lucas Stach Cc: Russell King Cc: Christian Gmeiner Cc: etnaviv@lists.freedesktop.org Link: https://patchwork.freedesktop.org/patch/msgid/20210301095254.1946084-1-daniel.vetter@ffwll.ch --- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/etnaviv/etnaviv_gem.c') diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 6d38c5c17f23..a9e696d05b33 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -689,7 +689,7 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj) struct page **pages = pvec + pinned; ret = pin_user_pages_fast(ptr, num_pages, - !userptr->ro ? FOLL_WRITE : 0, pages); + FOLL_WRITE | FOLL_FORCE, pages); if (ret < 0) { unpin_user_pages(pvec, pinned); kvfree(pvec); -- cgit v1.2.3