From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Rosenberg Subject: [PATCH] Fix out-of-bounds reading in sctp_asoc_get_hmac() Date: Fri, 01 Oct 2010 17:51:47 -0400 Message-ID: <1285969907.2814.49.camel@Dan> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-sctp@vger.kernel.org, linux-kernel@vger.kernel.org, security@kernel.org, stable@kernel.org, netdev@vger.kernel.org To: vladislav.yasevich@hp.com, sri@us.ibm.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 --- 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; }