From dffab154d29a288aa171ff50263ecc8f2e14a891 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Wed, 1 Feb 2017 11:58:09 +0100
Subject: [PATCH] su: properly clear child PID
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Reported-by: Tobias Stöckmann <tobias@stoeckmann.org>
Signed-off-by: Karel Zak <kzak@redhat.com>
---
 login-utils/su-common.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/login-utils/su-common.c b/login-utils/su-common.c
index 5aefd3f..696adc8 100644
--- a/login-utils/su-common.c
+++ b/login-utils/su-common.c
@@ -368,6 +368,9 @@ create_watching_parent (void)
             }
           else
             status = WEXITSTATUS (status);
+
+	  /* child is gone, don't use the PID anymore */
+	  child = (pid_t) -1;
         }
       else if (caught_signal)
         status = caught_signal + 128;
@@ -377,7 +380,7 @@ create_watching_parent (void)
   else
     status = 1;
 
-  if (caught_signal)
+  if (caught_signal && child != (pid_t)-1)
     {
       fprintf (stderr, _("\nSession terminated, killing shell..."));
       kill (child, SIGTERM);
@@ -387,9 +390,12 @@ create_watching_parent (void)
 
   if (caught_signal)
     {
-      sleep (2);
-      kill (child, SIGKILL);
-      fprintf (stderr, _(" ...killed.\n"));
+      if (child != (pid_t)-1)
+	{
+	  sleep (2);
+	  kill (child, SIGKILL);
+	  fprintf (stderr, _(" ...killed.\n"));
+	}
 
       /* Let's terminate itself with the received signal.
        *