[src/trunk]: src/sys/sys make CMSG_FIRSTHDR() validat emsg_controllen, as sug...

[itojun <itojun%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/7525a142c5f0
branches:  trunk
changeset: 514641:7525a142c5f0
user:      itojun <itojun%NetBSD.org@localhost>
date:      Fri Sep 07 08:13:01 2001 +0000

description:
make CMSG_FIRSTHDR() validat emsg_controllen, as suggested in RFC2292.
from kame

diffstat:

 sys/sys/socket.h |  11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diffs (25 lines):

diff -r c6769e8a4bcd -r 7525a142c5f0 sys/sys/socket.h
--- a/sys/sys/socket.h  Fri Sep 07 07:19:52 2001 +0000
+++ b/sys/sys/socket.h  Fri Sep 07 08:13:01 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: socket.h,v 1.61 2001/07/17 11:49:41 jdolecek Exp $     */
+/*     $NetBSD: socket.h,v 1.62 2001/09/07 08:13:01 itojun Exp $       */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -431,7 +431,14 @@
            (struct cmsghdr *)NULL : \
            (struct cmsghdr *)((caddr_t)(cmsg) + __CMSG_ALIGN((cmsg)->cmsg_len)))
 
-#define        CMSG_FIRSTHDR(mhdr)     ((struct cmsghdr *)(mhdr)->msg_control)
+/*
+ * RFC 2292 requires to check msg_controllen, in case that the kernel returns
+ * an empty list for some reasons.
+ */
+#define        CMSG_FIRSTHDR(mhdr) \
+       ((mhdr)->msg_controllen >= sizeof(struct cmsghdr) ? \
+        (struct cmsghdr *)(mhdr)->msg_control : \
+        (struct cmsghdr *)NULL)
 
 #define CMSG_SPACE(l)  (__CMSG_ALIGN(sizeof(struct cmsghdr)) + __CMSG_ALIGN(l))
 #define CMSG_LEN(l)    (__CMSG_ALIGN(sizeof(struct cmsghdr)) + (l))