From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756256Ab2FJLVQ (ORCPT ); Sun, 10 Jun 2012 07:21:16 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:51471 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755386Ab2FJLVO (ORCPT ); Sun, 10 Jun 2012 07:21:14 -0400 Date: Sun, 10 Jun 2012 12:24:35 +0100 From: Alan Cox To: Sasha Levin Cc: dbaryshkov@gmail.com, slapin@ossfans.org, davem@davemloft.net, linux-zigbee-devel@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ieee802154: verify packet size before trying to allocate it Message-ID: <20120610122435.7d5c8fa7@pyramind.ukuu.org.uk> In-Reply-To: <1339326619-1753-1-git-send-email-levinsasha928@gmail.com> References: <1339326619-1753-1-git-send-email-levinsasha928@gmail.com> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAFVBMVEWysKsSBQMIAwIZCwj///8wIhxoRDXH9QHCAAABeUlEQVQ4jaXTvW7DIBAAYCQTzz2hdq+rdg494ZmBeE5KYHZjm/d/hJ6NfzBJpp5kRb5PHJwvMPMk2L9As5Y9AmYRBL+HAyJKeOU5aHRhsAAvORQ+UEgAvgddj/lwAXndw2laEDqA4x6KEBhjYRCg9tBFCOuJFxg2OKegbWjbsRTk8PPhKPD7HcRxB7cqhgBRp9Dcqs+B8v4CQvFdqeot3Kov6hBUn0AJitrzY+sgUuiA8i0r7+B3AfqKcN6t8M6HtqQ+AOoELCikgQSbgabKaJW3kn5lBs47JSGDhhLKDUh1UMipwwinMYPTBuIBjEclSaGZUk9hDlTb5sUTYN2SFFQuPe4Gox1X0FZOufjgBiV1Vls7b+GvK3SU4wfmcGo9rPPQzgIabfj4TYQo15k3bTHX9RIw/kniir5YbtJF4jkFG+dsDK1IgE413zAthU/vR2HVMmFUPIHTvF6jWCpFaGw/A3qWgnbxpSm9MSmY5b3pM1gvNc/gQfwBsGwF0VCtxZgAAAAASUVORK5CYII= Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 10 Jun 2012 13:10:19 +0200 Sasha Levin wrote: > Currently when sending data over datagram, the send function will attempt to > allocate any size passed on from the userspace. > > We should make sure that this size is checked and limited. The maximum size > of an IP packet seemed like the safest limit here. > > Signed-off-by: Sasha Levin > --- > > Change in v2: > - Limit by maximum size the protocol supports. > > net/ieee802154/dgram.c | 5 +++++ > 1 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/net/ieee802154/dgram.c b/net/ieee802154/dgram.c > index 6fbb2ad..628498c 100644 > --- a/net/ieee802154/dgram.c > +++ b/net/ieee802154/dgram.c > @@ -232,6 +232,11 @@ static int dgram_sendmsg(struct kiocb *iocb, struct sock *sk, > > hlen = LL_RESERVED_SPACE(dev); > tlen = dev->needed_tailroom; > + if (hlen + tlen + size > IEEE802154_MTU) { > + err = -EMSGSIZE; > + goto out; What stops an overflow at this point. We'll then pass a small value to sock_alloc_send_skb/sock_alloc_send_pskb and copy a large number of bytes into it. This does seem to be already broken, and not fixed by the patch ? Alan