ceph: fix wrong sizeof argument issue in register_session()

The Coverity Scan service has detected the wrong sizeof
argument in register_session() [1]. The CID 1598909 defect
contains explanation: "The wrong sizeof value is used in
an expression or as argument to a function. The result is
an incorrect value that may cause unexpected program behaviors.
In register_session: The sizeof operator is invoked on
the wrong argument (CWE-569)".

The patch introduces a ptr_size variable that is initialized
by sizeof(struct ceph_mds_session *). And this variable is used
instead of sizeof(void *) in the code.

[1] https://scan5.scan.coverity.com/#/project-view/64304/10063?selectedIssue=1598909

Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Reviewed-by: Alex Markuze <amarkuze@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: dubeyko

fs/ceph/mds_client.c

@@ -979,14 +979,15 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	if (mds >= mdsc->max_sessions) {
 		int newmax = 1 << get_count_order(mds + 1);
 		struct ceph_mds_session **sa;
+		size_t ptr_size = sizeof(struct ceph_mds_session *);
 
 		doutc(cl, "realloc to %d\n", newmax);
-		sa = kcalloc(newmax, sizeof(void *), GFP_NOFS);
+		sa = kcalloc(newmax, ptr_size, GFP_NOFS);
 		if (!sa)
 			goto fail_realloc;
 		if (mdsc->sessions) {
 			memcpy(sa, mdsc->sessions,
-			       mdsc->max_sessions * sizeof(void *));
+			       mdsc->max_sessions * ptr_size);
 			kfree(mdsc->sessions);
 		}
 		mdsc->sessions = sa;