[src/trunk]: src/sys/kern Fix info leaks: the alignment of the structures cau...

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

details:   https://anonhg.NetBSD.org/src/rev/72a940e7e565
branches:  trunk
changeset: 461838:72a940e7e565
user:      maxv <maxv%NetBSD.org@localhost>
date:      Thu Jul 11 17:30:44 2019 +0000

description:
Fix info leaks: the alignment of the structures causes uninitialized heap
memory to be copied to userland in sys_recvmsg().

diffstat:

 sys/kern/uipc_socket2.c |  8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diffs (29 lines):

diff -r 7012f02854bb -r 72a940e7e565 sys/kern/uipc_socket2.c
--- a/sys/kern/uipc_socket2.c   Thu Jul 11 17:07:10 2019 +0000
+++ b/sys/kern/uipc_socket2.c   Thu Jul 11 17:30:44 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uipc_socket2.c,v 1.133 2018/11/04 16:30:29 christos Exp $      */
+/*     $NetBSD: uipc_socket2.c,v 1.134 2019/07/11 17:30:44 maxv Exp $  */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uipc_socket2.c,v 1.133 2018/11/04 16:30:29 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uipc_socket2.c,v 1.134 2019/07/11 17:30:44 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -1421,6 +1421,10 @@
        cp->cmsg_len = CMSG_LEN(size);
        cp->cmsg_level = level;
        cp->cmsg_type = type;
+
+       memset(cp + 1, 0, CMSG_LEN(0) - sizeof(*cp));
+       memset((uint8_t *)*p + size, 0, CMSG_ALIGN(size) - size);
+
        return m;
 }