From 4eb04f3974b9245e31a59b0910c7b81ac5bc0496 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tmraz@fedoraproject.org>
Date: Mon, 20 Jan 2014 17:12:53 +0100
Subject: pam_limits: detect and ignore stale utmp entries

Original idea by Christopher Hailey

* modules/pam_limits/pam_limits.c (check_logins): Use kill() to
detect if pid of the utmp entry is still running and ignore the entry
if it is not.
---
 modules/pam_limits/pam_limits.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/modules/pam_limits/pam_limits.c b/modules/pam_limits/pam_limits.c
index 8bf3b9bb..e2bc8e18 100644
--- a/modules/pam_limits/pam_limits.c
+++ b/modules/pam_limits/pam_limits.c
@@ -27,6 +27,7 @@
 #include <errno.h>
 #include <syslog.h>
 #include <stdarg.h>
+#include <signal.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/resource.h>
@@ -279,6 +280,12 @@ check_logins (pam_handle_t *pamh, const char *name, int limit, int ctrl,
 		&& !pam_modutil_user_in_group_nam_nam(pamh, ut->UT_USER, pl->login_group)) {
                 continue;
 	    }
+	    if (kill(ut->ut_pid, 0) == -1 && errno == ESRCH) {
+		/* process does not exist anymore */
+		pam_syslog(pamh, LOG_WARNING,
+			"Stale utmp entry (pid %d) for '%s' ignored", ut->ut_pid, name);
+		continue;
+	    }
 	}
 	if (++count > limit) {
 	    break;
-- 
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