[PATCH 03/13] Manage: fix check after dereference issue

[Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>]

The code dereferences dev_st earlier without checking, it gives SAST
problem.

dev_st is needed for attempt_re_add(), but it is executed only if
dv->disposition != 'S', so move disposition check up.

tst is a must to reach this place, dup_super() have to return valid
pointer, all it needs to check is if load_super() returns superblock.

Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
---
 Manage.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/Manage.c b/Manage.c
index 30302ac833f2..77b79cf57554 100644
--- a/Manage.c
+++ b/Manage.c
@@ -794,25 +794,23 @@ int Manage_add(int fd, int tfd, struct mddev_dev *dv,
 		 * simply re-add it.
 		 */
 
-		if (array->not_persistent == 0) {
+		if (array->not_persistent == 0 && dv->disposition != 'S') {
+			int rv = 0;
+
 			dev_st = dup_super(tst);
 			dev_st->ss->load_super(dev_st, tfd, NULL);
-			if (dev_st->sb && dv->disposition != 'S') {
-				int rv;
 
-				rv = attempt_re_add(fd, tfd, dv, dev_st, tst,
-						    rdev, update, devname,
-						    verbose, array);
-				dev_st->ss->free_super(dev_st);
-				if (rv) {
-					free(dev_st);
-					return rv;
-				}
-			}
-			if (dev_st) {
+			if (dev_st->sb) {
+				rv = attempt_re_add(fd, tfd, dv, dev_st, tst, rdev, update,
+						    devname, verbose, array);
+
 				dev_st->ss->free_super(dev_st);
-				free(dev_st);
 			}
+
+			free(dev_st);
+
+			if (rv)
+				return rv;
 		}
 		if (dv->disposition == 'M') {
 			if (verbose > 0)
-- 
2.35.3