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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 633FCC43441 for ; Sun, 11 Nov 2018 20:32:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F8EC20871 for ; Sun, 11 Nov 2018 20:32:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F8EC20871 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730630AbeKLGWY (ORCPT ); Mon, 12 Nov 2018 01:22:24 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50172 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730277AbeKLFsQ (ORCPT ); Mon, 12 Nov 2018 00:48:16 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gLvsc-0000oP-9t; Sun, 11 Nov 2018 19:58:46 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gLvsZ-0001pC-5V; Sun, 11 Nov 2018 19:58:43 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "syzbot" , "Willem de Bruijn" , "David S. Miller" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 312/366] packet: refine ring v3 block size test to hold one frame In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn commit 4576cd469d980317c4edd9173f8b694aa71ea3a3 upstream. TPACKET_V3 stores variable length frames in fixed length blocks. Blocks must be able to store a block header, optional private space and at least one minimum sized frame. Frames, even for a zero snaplen packet, store metadata headers and optional reserved space. In the block size bounds check, ensure that the frame of the chosen configuration fits. This includes sockaddr_ll and optional tp_reserve. Syzbot was able to construct a ring with insuffient room for the sockaddr_ll in the header of a zero-length frame, triggering an out-of-bounds write in dev_parse_header. Convert the comparison to less than, as zero is a valid snap len. This matches the test for minimum tp_frame_size immediately below. Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") Fixes: eb73190f4fbe ("net/packet: refine check for priv area size") Reported-by: syzbot Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/packet/af_packet.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3874,6 +3874,8 @@ static int packet_set_ring(struct sock * } if (req->tp_block_nr) { + unsigned int min_frame_size; + /* Sanity tests and some calculations */ err = -EBUSY; if (unlikely(rb->pg_vec)) @@ -3896,12 +3898,12 @@ static int packet_set_ring(struct sock * goto out; if (unlikely(req->tp_block_size & (PAGE_SIZE - 1))) goto out; + min_frame_size = po->tp_hdrlen + po->tp_reserve; if (po->tp_version >= TPACKET_V3 && - req->tp_block_size <= - BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv) + sizeof(struct tpacket3_hdr)) + req->tp_block_size < + BLK_PLUS_PRIV((u64)req_u->req3.tp_sizeof_priv) + min_frame_size) goto out; - if (unlikely(req->tp_frame_size < po->tp_hdrlen + - po->tp_reserve)) + if (unlikely(req->tp_frame_size < min_frame_size)) goto out; if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1))) goto out;