From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next-2.6] net: dev_addr_init() fix Date: Mon, 08 Jun 2009 14:13:32 +0200 Message-ID: <4A2D006C.70302@cosmosbay.com> References: <19f34abd0905301323k1498ca3fv31b271de65d60afc@mail.gmail.com> <1244408607.9064.8.camel@Maple> <19f34abd0906080300w796c6b65o6b537064cac917b0@mail.gmail.com> <4A2CEB9E.7080109@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: John Dykstra , Linux Netdev List , Ingo Molnar , Pekka Enberg , LKML , Jiri Pirko To: Vegard Nossum , "David S. Miller" Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:37323 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754629AbZFHMOE convert rfc822-to-8bit (ORCPT ); Mon, 8 Jun 2009 08:14:04 -0400 In-Reply-To: <4A2CEB9E.7080109@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Eric Dumazet a =C3=A9crit : > Vegard Nossum a =C3=A9crit : >> 2009/6/7 John Dykstra : >>> On Sat, 2009-05-30 at 22:23 +0200, Vegard Nossum wrote: >>>> It seems that loopback's hardware address is never initialized by = the >>>> kernel. So if userspace attempts to read this address before it ha= s >>>> been set, the kernel will return some uninitialized data (only 6 >>>> bytes, though). >>> Thank you for the report, Vegard. >>> >>> I've been unable to reproduce the problem you describe, using >>> 2.6-30-rc8, this test program and a couple of kernel builds for sys= tem >>> load: >> [...] >>> ------------------------------------------------------------------ >>> >>> Looking at the kernel code, it appears that all bytes of struct >>> net_device, including the L2 address, are initialized to zeros at >>> interface creation time. >>> >>> Can you spot a difference between your test procedures and mine tha= t >>> would enable me to reproduce the problem? >> Hi, >> >> I just tried your test program on a linux-next kernel, it works beau= tifully :-) >> >> (I made one change: The stack grows downwards on x86, so I think you >> should put child_stack + 16386 as the stack to clone()?) >> >> As I wrote in reply to Stephen Hemminger, this problem seems to be >> caused by a particular patch in linux-next: >> >> commit f001fde5eadd915f4858d22ed70d7040f48767cf >> Author: Jiri Pirko >> Date: Tue May 5 02:48:28 2009 +0000 >> >> net: introduce a list of device addresses dev_addr_list (v6) >> >=20 > I believe following patch should fix this problem. >=20 > Thank you >=20 > [PATCH net-next-2.6] net: loopback device dev->addr_len fix >=20 > commit f001fde5eadd915f4858d22ed70d7040f48767cf=20 > (net: introduce a list of device addresses dev_addr_list (v6)) > added one regression Vegard Nossum found in its testings. >=20 > loopback device doesnt have a hw address, we should set its > dev->addr_len to 0, not ETH_ALEN. >=20 > Reported-by: Vegard Nossum > Signed-off-by: Eric Dumazet Oh well, following is probably even more appropriate [PATCH net-next-2.6] net: dev_addr_init() fix commit f001fde5eadd915f4858d22ed70d7040f48767cf=20 (net: introduce a list of device addresses dev_addr_list (v6)) added one regression Vegard Nossum found in its testings. dev_addr_init() incorrectly uses sizeof() operator Reported-by: Vegard Nossum Signed-off-by: Eric Dumazet --- diff --git a/net/core/dev.c b/net/core/dev.c index 1f38401..65387d9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3655,8 +3655,8 @@ static int dev_addr_init(struct net_device *dev) /* rtnl_mutex must be held here */ =20 INIT_LIST_HEAD(&dev->dev_addr_list); - memset(addr, 0, sizeof(*addr)); - err =3D __hw_addr_add(&dev->dev_addr_list, NULL, addr, sizeof(*addr), + memset(addr, 0, sizeof(addr)); + err =3D __hw_addr_add(&dev->dev_addr_list, NULL, addr, sizeof(addr), NETDEV_HW_ADDR_T_LAN); if (!err) { /*