From: Ronny Chevalier <chevalier.ronny@gmail.com>
Date: Fri, 12 Jun 2015 09:37:11 +0000 (+0200)
Subject: login: fix potential null pointer dereference
X-Git-Tag: v226.4~1^2~293
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=c26ebdc9e7c5729dd2aa08c0cec8d8b1726afcef

login: fix potential null pointer dereference

Fix CID 1304686: Dereference after null check (FORWARD_NULL)

However, this commit does not fix any bug in logind. It helps to keep
the elect_display_compare() function generic.
---

diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index c0b473930..a9cf529e1 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -763,6 +763,9 @@ static int elect_display_compare(Session *s1, Session *s2) {
          * is preferred.
          *
          * s1 or s2 may be NULL. */
+        if (!s1 && !s2)
+                return 0;
+
         if ((s1 == NULL) != (s2 == NULL))
                 return (s1 == NULL) - (s2 == NULL);