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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 C8F8AC2D0B1 for ; Fri, 7 Feb 2020 07:25:06 +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 9F980214AF for ; Fri, 7 Feb 2020 07:25:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F980214AF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51014 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izy0f-0002xM-Qk for qemu-devel@archiver.kernel.org; Fri, 07 Feb 2020 02:25:05 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:58752) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izxyS-0000SV-Gn for qemu-devel@nongnu.org; Fri, 07 Feb 2020 02:22:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1izxyQ-0005dW-C5 for qemu-devel@nongnu.org; Fri, 07 Feb 2020 02:22:48 -0500 Received: from 8.mo2.mail-out.ovh.net ([188.165.52.147]:42523) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1izxyQ-0005a3-6d for qemu-devel@nongnu.org; Fri, 07 Feb 2020 02:22:46 -0500 Received: from player714.ha.ovh.net (unknown [10.108.35.240]) by mo2.mail-out.ovh.net (Postfix) with ESMTP id B65121C8F8F for ; Fri, 7 Feb 2020 08:22:43 +0100 (CET) Received: from kaod.org (82-64-250-170.subs.proxad.net [82.64.250.170]) (Authenticated sender: clg@kaod.org) by player714.ha.ovh.net (Postfix) with ESMTPSA id 779F5F082EC8; Fri, 7 Feb 2020 07:22:31 +0000 (UTC) Subject: Re: [PATCH v2 3/4] m25p80: Improve command handling for unsupported commands To: Guenter Roeck , Alistair Francis , Kevin Wolf References: <20200206183219.3756-1-linux@roeck-us.net> <20200206183219.3756-3-linux@roeck-us.net> From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Message-ID: Date: Fri, 7 Feb 2020 08:22:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200206183219.3756-3-linux@roeck-us.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Ovh-Tracer-Id: 1171780329806531504 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedugedrheeggddutdejucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecuhedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepuffvfhfhkffffgggjggtgfesthekredttdefjeenucfhrhhomhepveorughrihgtpgfnvggpifhorghtvghruceotghlgheskhgrohgurdhorhhgqeenucfkpheptddrtddrtddrtddpkedvrdeigedrvdehtddrudejtdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhhouggvpehsmhhtphdqohhuthdphhgvlhhopehplhgrhigvrhejudegrdhhrgdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomheptghlgheskhgrohgurdhorhhgpdhrtghpthhtohepqhgvmhhuqdguvghvvghlsehnohhnghhnuhdrohhrgh Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 188.165.52.147 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: Peter Maydell , qemu-block@nongnu.org, Andrew Jeffery , qemu-devel@nongnu.org, Max Reitz , qemu-arm@nongnu.org, Joel Stanley Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2/6/20 7:32 PM, Guenter Roeck wrote: > Whenever an unsupported command is encountered, the current code > interprets each transferred byte as new command. Most of the time, thos= e > 'commands' are interpreted as new unknown commands. However, in rare > cases, it may be that for example address or length information > passed with the original command is by itself a valid command. > If that happens, the state machine may get completely confused and, > worst case, start writing data into the flash or even erase it. >=20 > To avoid the problem, transition into STATE_READING_DATA and keep > sending a value of 0 until the chip is deselected after encountering > an unsupported command. >=20 > Signed-off-by: Guenter Roeck Reviewed-by: C=C3=A9dric Le Goater > --- > v2: Split patch into two parts; improved description. >=20 > hw/block/m25p80.c | 5 +++++ > 1 file changed, 5 insertions(+) >=20 > diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c > index 53bf63856f..8227088441 100644 > --- a/hw/block/m25p80.c > +++ b/hw/block/m25p80.c > @@ -1161,6 +1161,11 @@ static void decode_new_cmd(Flash *s, uint32_t va= lue) > s->quad_enable =3D false; > break; > default: > + s->pos =3D 0; > + s->len =3D 1; > + s->state =3D STATE_READING_DATA; > + s->data_read_loop =3D true; > + s->data[0] =3D 0; > qemu_log_mask(LOG_GUEST_ERROR, "M25P80: Unknown cmd %x\n", val= ue); > break; > } >=20