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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 6BC8CC43331 for ; Tue, 31 Mar 2020 13:26:39 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0999E20772 for ; Tue, 31 Mar 2020 13:26:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VHS98x/e" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0999E20772 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38014 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jJGuc-0007g4-5t for qemu-devel@archiver.kernel.org; Tue, 31 Mar 2020 09:26:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41909) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jJGq7-0000EY-77 for qemu-devel@nongnu.org; Tue, 31 Mar 2020 09:22:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jJGq5-0005fg-Pa for qemu-devel@nongnu.org; Tue, 31 Mar 2020 09:21:59 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:42836 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jJGq5-0005fL-L9 for qemu-devel@nongnu.org; Tue, 31 Mar 2020 09:21:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585660917; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tVkaJTRjt24I8sG8iS1Qlco78c4FvepcndOUPlDQIGU=; b=VHS98x/eEUvqGwtegn7v53a5wdvCWPaAVX0029AjkijQZPrfUM9Mm4+ZG2g9x/r4wGuJc+ DUXthrMG5Z4im4H5xvN/NNG8DFTP8+0F3FuX+tQK18SaYPtXEZD0Vev/vUYoy0m7EW4zdt /UhguZMEy7GXa0xLFn5bBvqAdjkmTXQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-41-2rmRCDZePc--G56XQiIJ7Q-1; Tue, 31 Mar 2020 09:21:55 -0400 X-MC-Unique: 2rmRCDZePc--G56XQiIJ7Q-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7E6531412; Tue, 31 Mar 2020 13:21:54 +0000 (UTC) Received: from jason-ThinkPad-T430s.redhat.com (ovpn-12-118.pek2.redhat.com [10.72.12.118]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1DB9110002BC; Tue, 31 Mar 2020 13:21:52 +0000 (UTC) From: Jason Wang To: qemu-devel@nongnu.org, peter.maydell@linaro.org Subject: [PULL V2 02/14] hw/net/i82596.c: Avoid reading off end of buffer in i82596_receive() Date: Tue, 31 Mar 2020 21:21:27 +0800 Message-Id: <1585660899-11228-3-git-send-email-jasowang@redhat.com> In-Reply-To: <1585660899-11228-1-git-send-email-jasowang@redhat.com> References: <1585660899-11228-1-git-send-email-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Wang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Peter Maydell The i82596_receive() function attempts to pass the guest a buffer which is effectively the concatenation of the data it is passed and a 4 byte CRC value. However, rather than implementing this as "write the data; then write the CRC" it instead bumps the length value of the data by 4, and writes 4 extra bytes from beyond the end of the buffer, which it then overwrites with the CRC. It also assumed that we could always fit all four bytes of the CRC into the final receive buffer, which might not be true if the CRC needs to be split over two receive buffers. Calculate separately how many bytes we need to transfer into the guest's receive buffer from the source buffer, and how many we need to transfer from the CRC work. We add a count 'bufsz' of the number of bytes left in the source buffer, which we use purely to assert() that we don't overrun. Spotted by Coverity (CID 1419396) for the specific case when we end up using a local array as the source buffer. Signed-off-by: Peter Maydell Signed-off-by: Jason Wang --- hw/net/i82596.c | 44 +++++++++++++++++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 9 deletions(-) diff --git a/hw/net/i82596.c b/hw/net/i82596.c index ecdb9aa..3b0efd0 100644 --- a/hw/net/i82596.c +++ b/hw/net/i82596.c @@ -497,7 +497,8 @@ ssize_t i82596_receive(NetClientState *nc, const uint8_= t *buf, size_t sz) uint32_t rfd_p; uint32_t rbd; uint16_t is_broadcast =3D 0; - size_t len =3D sz; + size_t len =3D sz; /* length of data for guest (including CRC) */ + size_t bufsz =3D sz; /* length of data in buf */ uint32_t crc; uint8_t *crc_ptr; uint8_t buf1[MIN_BUF_SIZE + VLAN_HLEN]; @@ -591,6 +592,7 @@ ssize_t i82596_receive(NetClientState *nc, const uint8_= t *buf, size_t sz) if (len < MIN_BUF_SIZE) { len =3D MIN_BUF_SIZE; } + bufsz =3D len; } =20 /* Calculate the ethernet checksum (4 bytes) */ @@ -623,6 +625,7 @@ ssize_t i82596_receive(NetClientState *nc, const uint8_= t *buf, size_t sz) while (len) { uint16_t buffer_size, num; uint32_t rba; + size_t bufcount, crccount; =20 /* printf("Receive: rbd is %08x\n", rbd); */ buffer_size =3D get_uint16(rbd + 12); @@ -635,14 +638,37 @@ ssize_t i82596_receive(NetClientState *nc, const uint= 8_t *buf, size_t sz) } rba =3D get_uint32(rbd + 8); /* printf("rba is 0x%x\n", rba); */ - address_space_write(&address_space_memory, rba, - MEMTXATTRS_UNSPECIFIED, buf, num); - rba +=3D num; - buf +=3D num; - len -=3D num; - if (len =3D=3D 0) { /* copy crc */ - address_space_write(&address_space_memory, rba - 4, - MEMTXATTRS_UNSPECIFIED, crc_ptr, 4); + /* + * Calculate how many bytes we want from buf[] and how many + * from the CRC. + */ + if ((len - num) >=3D 4) { + /* The whole guest buffer, we haven't hit the CRC yet */ + bufcount =3D num; + } else { + /* All that's left of buf[] */ + bufcount =3D len - 4; + } + crccount =3D num - bufcount; + + if (bufcount > 0) { + /* Still some of the actual data buffer to transfer */ + assert(bufsz >=3D bufcount); + bufsz -=3D bufcount; + address_space_write(&address_space_memory, rba, + MEMTXATTRS_UNSPECIFIED, buf, bufcount)= ; + rba +=3D bufcount; + buf +=3D bufcount; + len -=3D bufcount; + } + + /* Write as much of the CRC as fits */ + if (crccount > 0) { + address_space_write(&address_space_memory, rba, + MEMTXATTRS_UNSPECIFIED, crc_ptr, crcco= unt); + rba +=3D crccount; + crc_ptr +=3D crccount; + len -=3D crccount; } =20 num |=3D 0x4000; /* set F BIT */ --=20 2.5.0