[PATCH 4.4 21/92] audit: move calcs after alloc and check when logging set loginuid

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Guy Briggs <rgb@xxxxxxxxxx>

commit 76a658c20efd541a62838d9ff68ce94170d7a549 upstream.

Move the calculations of values after the allocation in case the
allocation fails.  This avoids wasting effort in the rare case that it
fails, but more importantly saves us extra logic to release the tty
ref.

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/auditsc.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1981,14 +1981,15 @@ static void audit_log_set_loginuid(kuid_
 	if (!audit_enabled)
 		return;
 
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_LOGIN);
+	if (!ab)
+		return;
+
 	uid = from_kuid(&init_user_ns, task_uid(current));
 	oldloginuid = from_kuid(&init_user_ns, koldloginuid);
 	loginuid = from_kuid(&init_user_ns, kloginuid),
 	tty = audit_get_tty(current);
 
-	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_LOGIN);
-	if (!ab)
-		return;
 	audit_log_format(ab, "pid=%d uid=%u", task_pid_nr(current), uid);
 	audit_log_task_context(ab);
 	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",