From 85fea2186392117575f2546c01e49efca78106c8 Mon Sep 17 00:00:00 2001
From: visa <visa@openbsd.org>
Date: Fri, 24 Aug 2018 12:45:27 +0000
Subject: [PATCH] Remove all knotes from a file descriptor before closing the
 file in fdfree(). This fixes a resource leak with cyclic kqueue references
 and prevents a kernel stack exhaustion scenario with long kqueue chains.

OK mpi@
---
 sys/kern/kern_descrip.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index a36a22f6b4b..f998b9c9147 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_descrip.c,v 1.181 2018/08/21 13:50:31 visa Exp $	*/
+/*	$OpenBSD: kern_descrip.c,v 1.182 2018/08/24 12:45:27 visa Exp $	*/
 /*	$NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $	*/
 
 /*
@@ -1169,6 +1169,7 @@ fdfree(struct proc *p)
 		fp = fdp->fd_ofiles[fd];
 		if (fp != NULL) {
 			fdp->fd_ofiles[fd] = NULL;
+			knote_fdclose(p, fd);
 			 /* closef() expects a refcount of 2 */
 			FREF(fp);
 			(void) closef(fp, p);
-- 
2.20.1