svn commit: r367582 - stable/12/sys/kern

[Konstantin Belousov]

Author: kib
Date: Wed Nov 11 00:43:13 2020
New Revision: 367582
URL: https://svnweb.freebsd.org/changeset/base/367582

Log:
  MFC r367120:
  Check for process group change in tty_wait_background().
  
  PR:	250701

Modified:
  stable/12/sys/kern/tty.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/tty.c
==============================================================================
--- stable/12/sys/kern/tty.c	Tue Nov 10 23:25:16 2020	(r367581)
+++ stable/12/sys/kern/tty.c	Wed Nov 11 00:43:13 2020	(r367582)
@@ -464,6 +464,19 @@ tty_wait_background(struct tty *tp, struct thread *td,
 			sig = 0;
 		}
 		PGRP_LOCK(pg);
+
+		/*
+		 * pg may no longer be our process group.
+		 * Re-check after locking process group.
+		 */
+		PROC_LOCK(p);
+		if (p->p_pgrp != pg) {
+			PROC_UNLOCK(p);
+			PGRP_UNLOCK(pg);
+			continue;
+		}
+
+		PROC_UNLOCK(p);
 		pgsignal(pg, ksi.ksi_signo, 1, &ksi);
 		PGRP_UNLOCK(pg);