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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01AD0C7EE22 for ; Wed, 17 May 2023 05:10:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230077AbjEQFKj (ORCPT ); Wed, 17 May 2023 01:10:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231691AbjEQFKh (ORCPT ); Wed, 17 May 2023 01:10:37 -0400 Received: from smtp.gentoo.org (smtp.gentoo.org [IPv6:2001:470:ea4a:1:5054:ff:fec7:86e4]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A2D22136; Tue, 16 May 2023 22:10:27 -0700 (PDT) Message-ID: <9f0a43e5-9f9b-b77b-d882-627251e585cc@gentoo.org> Date: Wed, 17 May 2023 07:10:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 From: zzam@gentoo.org Subject: Re: [PATCH 05/24] media: dvb-usb-v2: ec168: fix null-ptr-deref in ec168_i2c_xfer() Content-Language: en-GB To: Mauro Carvalho Chehab Cc: Wei Chen , Antti Palosaari , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org References: <53558de2b5c4f4ee6bfcfbe34e27071c2d0073d5.1684000646.git.mchehab@kernel.org> <7ced9f219d36cb0d3319b556dc0b0f4f81247fa6.1684000646.git.mchehab@kernel.org> In-Reply-To: <7ced9f219d36cb0d3319b556dc0b0f4f81247fa6.1684000646.git.mchehab@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 13.05.23 um 19:57 schrieb Mauro Carvalho Chehab: > From: Wei Chen > > In ec168_i2c_xfer, msg is controlled by user. When msg[i].buf is null > and msg[i].len is zero, former checks on msg[i].buf would be passed. > If accessing msg[i].buf[0] without sanity check, null pointer deref > would happen. We add check on msg[i].len to prevent crash. > > Similar commit: > commit 0ed554fd769a ("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()") > Review comment below. > Link: https://lore.kernel.org/linux-media/20230313085853.3252349-1-harperchen1110@gmail.com > Signed-off-by: Wei Chen > Signed-off-by: Mauro Carvalho Chehab > --- > drivers/media/usb/dvb-usb-v2/ec168.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/media/usb/dvb-usb-v2/ec168.c b/drivers/media/usb/dvb-usb-v2/ec168.c > index 7ed0ab9e429b..0e4773fc025c 100644 > --- a/drivers/media/usb/dvb-usb-v2/ec168.c > +++ b/drivers/media/usb/dvb-usb-v2/ec168.c > @@ -115,6 +115,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > while (i < num) { > if (num > i + 1 && (msg[i+1].flags & I2C_M_RD)) { > if (msg[i].addr == ec168_ec100_config.demod_address) { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } > req.cmd = READ_DEMOD; > req.value = 0; > req.index = 0xff00 + msg[i].buf[0]; /* reg */ > @@ -131,6 +135,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > } > } else { > if (msg[i].addr == ec168_ec100_config.demod_address) { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } The check condition should be msg[i].len < 2 or != 2. The following lines access msg[i].buf elements 0 and 1. > req.cmd = WRITE_DEMOD; > req.value = msg[i].buf[1]; /* val */ > req.index = 0xff00 + msg[i].buf[0]; /* reg */ > @@ -139,6 +147,10 @@ static int ec168_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], > ret = ec168_ctrl_msg(d, &req); > i += 1; > } else { > + if (msg[i].len < 1) { > + i = -EOPNOTSUPP; > + break; > + } > req.cmd = WRITE_I2C; > req.value = msg[i].buf[0]; /* val */ > req.index = 0x0100 + msg[i].addr; /* I2C addr */