Module Name: src
Committed By: ozaki-r
Date: Wed Feb 15 01:48:44 UTC 2017
Modified Files:
src/sys/net: if.c
Log Message:
Avoid if_dl and if_sadl to be NULL
Calling if_deactivate_sadl and then if_sadl_setrefs exposes NULL-ed if_dl
and if_sadl to users for a moment. It's harmful because users expect that
they're always non-NULL. Fix it.
Note that a race condition still remains; if_dl and if_sald aren't updated
atomically so a user can see different data from if_dl and if_sadl.
Fortunately none uses both if_dl and if_sadl at the same time, so the race
condition doesn't hurt nobody for now. (In the first place exposing one
data with two ways is problematic?)
To generate a diff of this commit:
cvs rdiff -u -r1.377 -r1.378 src/sys/net/if.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/net/if.c
diff -u src/sys/net/if.c:1.377 src/sys/net/if.c:1.378
--- src/sys/net/if.c:1.377 Fri Feb 10 20:56:21 2017
+++ src/sys/net/if.c Wed Feb 15 01:48:44 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: if.c,v 1.377 2017/02/10 20:56:21 christos Exp $ */
+/* $NetBSD: if.c,v 1.378 2017/02/15 01:48:44 ozaki-r Exp $ */
/*-
* Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
@@ -90,7 +90,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.377 2017/02/10 20:56:21 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.378 2017/02/15 01:48:44 ozaki-r Exp $");
#if defined(_KERNEL_OPT)
#include "opt_inet.h"
@@ -518,6 +518,23 @@ if_deactivate_sadl(struct ifnet *ifp)
ifafree(ifa);
}
+static void
+if_replace_sadl(struct ifnet *ifp, struct ifaddr *ifa)
+{
+ struct ifaddr *old;
+
+ KASSERT(ifp->if_dl != NULL);
+
+ old = ifp->if_dl;
+
+ ifaref(ifa);
+ /* XXX Update if_dl and if_sadl atomically */
+ ifp->if_dl = ifa;
+ ifp->if_sadl = satosdl(ifa->ifa_addr);
+
+ ifafree(old);
+}
+
void
if_activate_sadl(struct ifnet *ifp, struct ifaddr *ifa0,
const struct sockaddr_dl *sdl)
@@ -526,11 +543,11 @@ if_activate_sadl(struct ifnet *ifp, stru
struct ifaddr *ifa;
int bound = curlwp_bind();
- s = splsoftnet();
+ KASSERT(ifa_held(ifa0));
- if_deactivate_sadl(ifp);
+ s = splsoftnet();
- if_sadl_setrefs(ifp, ifa0);
+ if_replace_sadl(ifp, ifa0);
ss = pserialize_read_enter();
IFADDR_READER_FOREACH(ifa, ifp) {
