From: jsing <jsing@openbsd.org>
Date: Fri, 10 Aug 2018 15:53:49 +0000 (+0000)
Subject: Update fd_freefile when filtering/closing kqueue descriptors in fdcopy().
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=9406475e8b3ea5593448995104226950635465a6;p=openbsd

Update fd_freefile when filtering/closing kqueue descriptors in fdcopy().

Prior to r1.153 of kern_descrip.c, the kqueue descriptors were removed
using fdremove(), which reset fd_freefile as appropriate. The new code
simply avoids adding the descriptor to the new table, however this means
that fd_freefile can be left with an incorrect value, resulting in a file
descriptor allocation "hole". Restore the previous behavour by lowering
fd_freefile as appropriate when dropping descriptors.

Issue found via golang regress tests.

ok deraadt@ mpi@ visa@
---

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 831d8015dd7..4224a87274d 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_descrip.c,v 1.177 2018/07/10 08:58:50 mpi Exp $	*/
+/*	$OpenBSD: kern_descrip.c,v 1.178 2018/08/10 15:53:49 jsing Exp $	*/
 /*	$NetBSD: kern_descrip.c,v 1.42 1996/03/30 22:24:38 christos Exp $	*/
 
 /*
@@ -1143,8 +1143,11 @@ fdcopy(struct process *pr)
 			 * their internal consistency, so close them here.
 			 */
 			if (fp->f_count >= FDUP_MAX_COUNT ||
-			    fp->f_type == DTYPE_KQUEUE)
+			    fp->f_type == DTYPE_KQUEUE) {
+				if (i < newfdp->fd_freefile)
+					newfdp->fd_freefile = i;
 				continue;
+			}
 
 			FREF(fp);
 			newfdp->fd_ofiles[i] = fp;