From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58738C433FE for ; Mon, 1 Nov 2021 09:24:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 41168611C6 for ; Mon, 1 Nov 2021 09:24:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232068AbhKAJ0q (ORCPT ); Mon, 1 Nov 2021 05:26:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:59239 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232540AbhKAJXn (ORCPT ); Mon, 1 Nov 2021 05:23:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 80B6161167; Mon, 1 Nov 2021 09:21:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1635758462; bh=08W/I7l8cfPYuaLmXeJX9hxRo/5kGORstL0bzuPrZPw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b/oGRj5riGRXDVvrNJxDatRNKrRfU4ARRVuN33vU9PWtGuyvOTnJsN1PJngEzG9oT tnZvOjwwVO1xehv2H5fGGX/b6d9Wf476WsE+AAiMBFKs5jFCTF5xNzmdrMY4dpGbx3 ahLzdeRqkX67h7x6z+UszRRxsRx/k14mjGk6uZFU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xin Long , Marcelo Ricardo Leitner , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.14 24/25] sctp: add vtag check in sctp_sf_do_8_5_1_E_sa Date: Mon, 1 Nov 2021 10:17:36 +0100 Message-Id: <20211101082452.757400870@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211101082447.070493993@linuxfoundation.org> References: <20211101082447.070493993@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xin Long [ Upstream commit ef16b1734f0a176277b7bb9c71a6d977a6ef3998 ] sctp_sf_do_8_5_1_E_sa() is called when processing SHUTDOWN_ACK chunk in cookie_wait and cookie_echoed state. The vtag in the chunk's sctphdr should be verified, otherwise, as later in chunk length check, it may send abort with the existent asoc's vtag, which can be exploited by one to cook a malicious chunk to terminate a SCTP asoc. Note that when fails to verify the vtag from SHUTDOWN-ACK chunk, SHUTDOWN COMPLETE message will still be sent back to peer, but with the vtag from SHUTDOWN-ACK chunk, as said in 5) of rfc4960#section-8.4. While at it, also remove the unnecessary chunk length check from sctp_sf_shut_8_4_5(), as it's already done in both places where it calls sctp_sf_shut_8_4_5(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sctp/sm_statefuns.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index e6260946eafe..c3cb0ae7df2b 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -3613,12 +3613,6 @@ static enum sctp_disposition sctp_sf_shut_8_4_5( SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); - /* If the chunk length is invalid, we don't want to process - * the reset of the packet. - */ - if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) - return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); - /* We need to discard the rest of the packet to prevent * potential bomming attacks from additional bundled chunks. * This is documented in SCTP Threats ID. @@ -3646,6 +3640,9 @@ enum sctp_disposition sctp_sf_do_8_5_1_E_sa(struct net *net, { struct sctp_chunk *chunk = arg; + if (!sctp_vtag_verify(chunk, asoc)) + asoc = NULL; + /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, -- 2.33.0