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 0E23CC433FE for ; Tue, 5 Oct 2021 10:06:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E84FD61505 for ; Tue, 5 Oct 2021 10:06:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233896AbhJEKID (ORCPT ); Tue, 5 Oct 2021 06:08:03 -0400 Received: from relay07.th.seeweb.it ([5.144.164.168]:52257 "EHLO relay07.th.seeweb.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233365AbhJEKIC (ORCPT ); Tue, 5 Oct 2021 06:08:02 -0400 Received: from SoMainline.org (94-209-165-62.cable.dynamic.v4.ziggo.nl [94.209.165.62]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by m-r2.th.seeweb.it (Postfix) with ESMTPSA id C2A4E3EE89; Tue, 5 Oct 2021 12:06:07 +0200 (CEST) Date: Tue, 5 Oct 2021 12:06:06 +0200 From: Marijn Suijten To: Daniel Thompson Cc: phone-devel@vger.kernel.org, Andy Gross , Bjorn Andersson , Lee Jones , Jingoo Han , ~postmarketos/upstreaming@lists.sr.ht, AngeloGioacchino Del Regno , Konrad Dybcio , Martin Botka , Jami Kettunen , Pavel Dubrova , Kiran Gunda , Courtney Cavin , Bryan Wu , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/10] backlight: qcom-wled: Fix off-by-one maximum with default num_strings Message-ID: <20211005100606.faxra73mzkvjd4f6@SoMainline.org> Mail-Followup-To: Daniel Thompson , phone-devel@vger.kernel.org, Andy Gross , Bjorn Andersson , Lee Jones , Jingoo Han , ~postmarketos/upstreaming@lists.sr.ht, AngeloGioacchino Del Regno , Konrad Dybcio , Martin Botka , Jami Kettunen , Pavel Dubrova , Kiran Gunda , Courtney Cavin , Bryan Wu , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20211004192741.621870-1-marijn.suijten@somainline.org> <20211004192741.621870-6-marijn.suijten@somainline.org> <20211005091947.7msztp5l554c7cy4@maple.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211005091947.7msztp5l554c7cy4@maple.lan> Precedence: bulk List-ID: X-Mailing-List: phone-devel@vger.kernel.org On 2021-10-05 10:19:47, Daniel Thompson wrote: > On Mon, Oct 04, 2021 at 09:27:36PM +0200, Marijn Suijten wrote: > > When not specifying num-strings in the DT the default is used, but +1 is > > added to it which turns wled3 into 4 and wled4/5 into 5 strings instead > > of 3 and 4 respectively, causing out of bounds reads and register > > read/writes. This +1 exists for a deficiency in the DT parsing code, > > and is simply omitted entirely - solving this oob issue - by allowing > > one extra iteration of the wled_var_cfg function parsing this particular > > property. > > > > Fixes: 93c64f1ea1e8 ("leds: add Qualcomm PM8941 WLED driver") > > Signed-off-by: Marijn Suijten > > Reviewed-by: AngeloGioacchino Del Regno > > --- > > drivers/video/backlight/qcom-wled.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c > > index 27e8949c7922..66ce77ee3099 100644 > > --- a/drivers/video/backlight/qcom-wled.c > > +++ b/drivers/video/backlight/qcom-wled.c > > @@ -1255,17 +1255,17 @@ static const struct wled_var_cfg wled5_ovp_cfg = { > > > > static u32 wled3_num_strings_values_fn(u32 idx) > > { > > - return idx + 1; > > + return idx; > > } > > > > static const struct wled_var_cfg wled3_num_strings_cfg = { > > .fn = wled3_num_strings_values_fn, > > - .size = 3, > > + .size = 4, /* [0, 3] */ > > 0 is not a valid value for this property. These comments represent the possible loop iterations the DT "cfg parser" runs through, starting at j=0 and running up until and including j=3. Should I make that more clear or omit these comments entirely? - Marijn > > }; > > > > static const struct wled_var_cfg wled4_num_strings_cfg = { > > .fn = wled3_num_strings_values_fn, > > - .size = 4, > > + .size = 5, /* [0, 4] */ > > Ditto. > > > > }; > > > > static u32 wled3_switch_freq_values_fn(u32 idx) > > @@ -1520,8 +1520,6 @@ static int wled_configure(struct wled *wled) > > *bool_opts[i].val_ptr = true; > > } > > > > - cfg->num_strings = cfg->num_strings + 1; > > - > > string_len = of_property_count_elems_of_size(dev->of_node, > > "qcom,enabled-strings", > > sizeof(u32)); > > -- > > 2.33.0 > >