On Fri, May 3, 2019 at 6:56 PM Catalin Marinas catalin.marinas@arm.com wrote:
On Tue, Apr 30, 2019 at 03:25:06PM +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.
userfaultfd_register() and userfaultfd_unregister() use provided user pointers for vma lookups, which can only by done with untagged pointers.
Untag user pointers in these functions.
Signed-off-by: Andrey Konovalov andreyknvl@google.com
fs/userfaultfd.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index f5de1e726356..fdee0db0e847 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1325,6 +1325,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, goto out; }
uffdio_register.range.start =untagged_addr(uffdio_register.range.start);ret = validate_range(mm, uffdio_register.range.start, uffdio_register.range.len); if (ret)@@ -1514,6 +1517,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) goto out;
uffdio_unregister.start = untagged_addr(uffdio_unregister.start);ret = validate_range(mm, uffdio_unregister.start, uffdio_unregister.len); if (ret)Wouldn't it be easier to do this in validate_range()? There are a few more calls in this file, though I didn't check whether a tagged address would cause issues.
Yes, I think it makes more sense, will do in v15, thanks!
-- Catalin