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 E9B92C433F5 for ; Mon, 1 Nov 2021 09:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D205861458 for ; Mon, 1 Nov 2021 09:32:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232864AbhKAJeb (ORCPT ); Mon, 1 Nov 2021 05:34:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:37280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232929AbhKAJa0 (ORCPT ); Mon, 1 Nov 2021 05:30:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7F6BB61100; Mon, 1 Nov 2021 09:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1635758635; bh=uuvCZinPlVVtB987oHRchMjM23YEZ9GKFrWDsBGRH9E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GUOaIOe2m2nYLZuUBY9M6MC3OJR2b1wsJ3wJfDPzlSoQQTeBUXv3JwcH51n3jT5M2 nrBH4PAF0jNekhuj/PX81BTodoq/Pe3AtV1AyWjqmfpZT4dtAFH7IO6VuTDnN6JItv UrcwTrnlg8ISE070+sEp2Yoo//Pcnjkreb8HCeFU= 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 5.4 45/51] sctp: add vtag check in sctp_sf_do_8_5_1_E_sa Date: Mon, 1 Nov 2021 10:17:49 +0100 Message-Id: <20211101082511.128109616@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211101082500.203657870@linuxfoundation.org> References: <20211101082500.203657870@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 35701acbed73..877420868a42 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -3683,12 +3683,6 @@ 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. @@ -3716,6 +3710,9 @@ 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