From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH] Fix out-of-bounds reading in sctp_asoc_get_hmac() Date: Fri, 01 Oct 2010 18:13:34 -0400 Message-ID: <4CA65D0E.6080604@hp.com> References: <1285969907.2814.49.camel@Dan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: sri@us.ibm.com, linux-sctp@vger.kernel.org, linux-kernel@vger.kernel.org, security@kernel.org, stable@kernel.org, netdev@vger.kernel.org To: Dan Rosenberg Return-path: In-Reply-To: <1285969907.2814.49.camel@Dan> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 10/01/2010 05:51 PM, Dan Rosenberg wrote: > The sctp_asoc_get_hmac() function iterates through a peer's hmac_ids > array and attempts to ensure that only a supported hmac entry is > returned. The current code fails to do this properly - if the last id > in the array is out of range (greater than SCTP_AUTH_HMAC_ID_MAX), the > id integer remains set after exiting the loop, and the address of an > out-of-bounds entry will be returned and subsequently used in the parent > function, causing potentially ugly memory corruption. This patch resets > the id integer to 0 on encountering an invalid id so that NULL will be > returned after finishing the loop if no valid ids are found. > > Signed-off-by: Dan Rosenberg Good catch. Acked-by: Vlad Yasevich -vlad > > --- linux-2.6.35.5.orig/net/sctp/auth.c 2010-09-20 16:59:09.000000000 -0400 > +++ linux-2.6.35.5/net/sctp/auth.c 2010-10-01 16:48:58.000000000 -0400 > @@ -543,16 +543,20 @@ struct sctp_hmac *sctp_auth_asoc_get_hma > id = ntohs(hmacs->hmac_ids[i]); > > /* Check the id is in the supported range */ > - if (id> SCTP_AUTH_HMAC_ID_MAX) > + if (id> SCTP_AUTH_HMAC_ID_MAX) { > + id = 0; > continue; > + } > > /* See is we support the id. Supported IDs have name and > * length fields set, so that we can allocated and use > * them. We can safely just check for name, for without the > * name, we can't allocate the TFM. > */ > - if (!sctp_hmac_list[id].hmac_name) > + if (!sctp_hmac_list[id].hmac_name) { > + id = 0; > continue; > + } > > break; > } > >