From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Sharlaimov Subject: [RFC] [PATCH 2.6.21.5] ppp: fix osize too small errors when decoding mppe Date: Wed, 20 Jun 2007 22:37:18 +1100 Message-ID: <4679116E.9050507@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1251 Content-Transfer-Encoding: 7bit Cc: Sergey Vlasov , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Paul Mackerras Return-path: Received: from ik-out-1112.google.com ([66.249.90.179]:16247 "EHLO ik-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751750AbXFTLhf (ORCPT ); Wed, 20 Jun 2007 07:37:35 -0400 Received: by ik-out-1112.google.com with SMTP id b32so134244ika for ; Wed, 20 Jun 2007 04:37:34 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The mppe_decompress() function required a buffer that is 1 byte too small when receiving a message of mru size. This fixes buffer allocation to prevent this from occurring. Signed-off-by: Konstantin Sharlaimov --- As Sergey Vlasov pointed out, ppp_mppe-account-for-osize-too-small-errors-in.patch may cause buffer overflows on certain data. Here is another patch that should eliminate the "osize too small" errors. Instead of patching mppe_decompress itself, I have patched ppp_decompress_frame so it would allocate the required extra byte when using mppe compression. I didn't have a chance to check this patch carefully yet, but it seem to be working as expected. Any comments would be greatly appreciated. --- linux-2.6.21.3/drivers/net/ppp_generic.c.orig 2007-06-20 09:14:13.000000000 +1100 +++ linux-2.6.21.3/drivers/net/ppp_generic.c 2007-06-20 09:18:06.000000000 +1100 @@ -1711,7 +1711,18 @@ ppp_decompress_frame(struct ppp *ppp, st goto err; if (proto == PPP_COMP) { - ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN); + int obuff_size; + + switch(ppp->rcomp->compress_proto) { + case CI_MPPE: + obuff_size = ppp->mru + PPP_HDRLEN + 1; + break; + default: + obuff_size = ppp->mru + PPP_HDRLEN; + break; + } + + ns = dev_alloc_skb(obuff_size); if (ns == 0) { printk(KERN_ERR "ppp_decompress_frame: no memory\n"); goto err;