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 <andreyk...@google.com>
---
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)
--
2.21.0.225.g810b269d1ac-goog
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