From b85282ba08b1fc57e1ef8f408bbb8b3ba0b4835e Mon Sep 17 00:00:00 2001
From: Maxim Konovalov <maxim@FreeBSD.org>
Date: Thu, 14 Feb 2002 15:26:59 +0000
Subject: [PATCH] Prevent dup2(2) from closing internal libc_r pipe
 descriptors.

PR:		misc/28947
Reviewed by:	jasone, ru
Approved by:	jasone, ru
MFC after:	1 week
---
 lib/libc_r/uthread/uthread_dup2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/libc_r/uthread/uthread_dup2.c b/lib/libc_r/uthread/uthread_dup2.c
index 6e8195ba17c..af0e32aff5b 100644
--- a/lib/libc_r/uthread/uthread_dup2.c
+++ b/lib/libc_r/uthread/uthread_dup2.c
@@ -45,7 +45,8 @@ _dup2(int fd, int newfd)
 	int		newfd_opened;
 
 	/* Check if the file descriptor is out of range: */
-	if (newfd < 0 || newfd >= _thread_dtablesize) {
+	if (newfd < 0 || newfd >= _thread_dtablesize ||
+	    newfd == _thread_kern_pipe[0] || newfd == _thread_kern_pipe[1]) {
 		/* Return a bad file descriptor error: */
 		errno = EBADF;
 		ret = -1;