[src/trunk]: src/sys/kern From tedu at openbsd:

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

details:   https://anonhg.NetBSD.org/src/rev/5df1205a5325
branches:  trunk
changeset: 346467:5df1205a5325
user:      christos <christos%NetBSD.org@localhost>
date:      Thu Jul 14 06:22:17 2016 +0000

description:
>From tedu at openbsd:

kevent validates that ident is a valid fd by getting the file. one sad
quirk: uint64 to int32 truncation can lead to false positives, and then
later in the array sizing code, very big mallocs panic the kernel.
add a check that the ident isn't larger than INT_MAX in the fd case.
reported by Tim Newsham

diffstat:

 sys/kern/kern_event.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (28 lines):

diff -r 5d6622c2a921 -r 5df1205a5325 sys/kern/kern_event.c
--- a/sys/kern/kern_event.c     Thu Jul 14 05:00:51 2016 +0000
+++ b/sys/kern/kern_event.c     Thu Jul 14 06:22:17 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_event.c,v 1.86 2016/04/04 20:47:57 christos Exp $ */
+/*     $NetBSD: kern_event.c,v 1.87 2016/07/14 06:22:17 christos Exp $ */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.86 2016/04/04 20:47:57 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.87 2016/07/14 06:22:17 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -935,6 +935,9 @@
        /* search if knote already exists */
        if (kfilter->filtops->f_isfd) {
                /* monitoring a file descriptor */
+               /* validate descriptor */
+               if (kev->ident > INT_MAX)
+                       return EBADF;
                fd = kev->ident;
                if ((fp = fd_getfile(fd)) == NULL) {
                        rw_exit(&kqueue_filter_lock);