[PATCH v10 07/12] fs, arm64: untag user pointers in fs/userfaultfd.c

From: Andrey Konovalov
Date: Fri Feb 22 2019 - 07:53:50 EST


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@xxxxxxxxxx>
---
fs/userfaultfd.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 89800fc7dc9d..a3b70e0d9756 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1320,6 +1320,9 @@ 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)
@@ -1507,6 +1510,8 @@ 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)
--
2.21.0.rc0.258.g878e2cd30e-goog