[PATCH] ceph: Annotate struct ceph_osd_request with __counted_by

[Kees Cook <keescook@chromium.org>]

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct ceph_osd_request.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Xiubo Li <xiubli@redhat.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: ceph-devel@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/ceph/osd_client.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index bf9823956758..b8610e9d2471 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -278,7 +278,7 @@ struct ceph_osd_request {
 	int r_attempts;
 	u32 r_map_dne_bound;
 
-	struct ceph_osd_req_op r_ops[];
+	struct ceph_osd_req_op r_ops[] __counted_by(r_num_ops);
 };
 
 struct ceph_request_redirect {
-- 
2.34.1