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 DE56BECAAA1 for ; Fri, 28 Oct 2022 15:35:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229874AbiJ1PfX (ORCPT ); Fri, 28 Oct 2022 11:35:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229510AbiJ1PfU (ORCPT ); Fri, 28 Oct 2022 11:35:20 -0400 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB80E5AA01; Fri, 28 Oct 2022 08:35:15 -0700 (PDT) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id F29EC1C09E5; Fri, 28 Oct 2022 17:35:13 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ucw.cz; s=gen1; t=1666971313; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=NZ+XC4iEcro/8zXcMRHQx9f6mpwLNOhOuYFKcJdBGUA=; b=KyY770jITqm/kV0UkVD96zlokENQ8wQv5fmjhAsHoiAUv3+H95RR1GHp47r6vDXgzAWkoP jyKeT/+t7UX+Z1VKq+y8zSA34lBha8BTtH/ooGNPBDrMXmaWGrwCyWZfW0egCLBcRmNbRJ 4NReokL4i9zkvQbKBEwzwrZ3KlDYiDA= Date: Fri, 28 Oct 2022 17:34:57 +0200 From: Pavel Machek To: Maarten Zanders Cc: Arne Staessen , linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] leds: lp5523: fix out-of-bounds bug in lp5523_selftest() Message-ID: <20221028153457.GA14936@duo.ucw.cz> References: <20221028105643.45300-1-maarten.zanders@mind.be> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="azLHFNyN32YCQGCU" Content-Disposition: inline In-Reply-To: <20221028105643.45300-1-maarten.zanders@mind.be> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --azLHFNyN32YCQGCU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > When not all LED channels of the led chip are configured, the > sysfs selftest functionality gives erroneous results and tries to > test all channels of the chip. > There is a potential for LED overcurrent conditions since the > test current will be set to values from out-of-bound regions. >=20 > It is wrong to use pdata->led_config[i].led_current to skip absent > channels as led_config[] only contains the configured LED channels. >=20 > Instead of iterating over all the physical channels of the device, > loop over the available LED configurations and use led->chan_nr to > access the correct i2c registers. Keep the zero-check for the LED > current as existing users might depend on this to disable a channel. Thanks, applied, I'll push eventually. I wonder, should we do these kind of actions on attribute _read_? I'd preffer some kind of write action to trigger this. Best regards, Pavel > Reported-by: Arne Staessen > Signed-off-by: Maarten Zanders > --- > drivers/leds/leds-lp5523.c | 27 +++++++++++++++------------ > 1 file changed, 15 insertions(+), 12 deletions(-) >=20 > diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c > index 369d40b0b65b..e08e3de1428d 100644 > --- a/drivers/leds/leds-lp5523.c > +++ b/drivers/leds/leds-lp5523.c > @@ -581,8 +581,8 @@ static ssize_t lp5523_selftest(struct device *dev, > struct lp55xx_led *led =3D i2c_get_clientdata(to_i2c_client(dev)); > struct lp55xx_chip *chip =3D led->chip; > struct lp55xx_platform_data *pdata =3D chip->pdata; > - int i, ret, pos =3D 0; > - u8 status, adc, vdd; > + int ret, pos =3D 0; > + u8 status, adc, vdd, i; > =20 > mutex_lock(&chip->lock); > =20 > @@ -612,20 +612,21 @@ static ssize_t lp5523_selftest(struct device *dev, > =20 > vdd--; /* There may be some fluctuation in measurement */ > =20 > - for (i =3D 0; i < LP5523_MAX_LEDS; i++) { > - /* Skip non-existing channels */ > + for (i =3D 0; i < pdata->num_channels; i++) { > + /* Skip disabled channels */ > if (pdata->led_config[i].led_current =3D=3D 0) > continue; > =20 > /* Set default current */ > - lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + i, > + lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + led->chan_nr, > pdata->led_config[i].led_current); > =20 > - lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + i, 0xff); > + lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr, > + 0xff); > /* let current stabilize 2 - 4ms before measurements start */ > usleep_range(2000, 4000); > lp55xx_write(chip, LP5523_REG_LED_TEST_CTRL, > - LP5523_EN_LEDTEST | i); > + LP5523_EN_LEDTEST | led->chan_nr); > /* ADC conversion time is 2.7 ms typically */ > usleep_range(3000, 6000); > ret =3D lp55xx_read(chip, LP5523_REG_STATUS, &status); > @@ -633,20 +634,22 @@ static ssize_t lp5523_selftest(struct device *dev, > goto fail; > =20 > if (!(status & LP5523_LEDTEST_DONE)) > - usleep_range(3000, 6000);/* Was not ready. Wait. */ > + usleep_range(3000, 6000); /* Was not ready. Wait. */ > =20 > ret =3D lp55xx_read(chip, LP5523_REG_LED_TEST_ADC, &adc); > if (ret < 0) > goto fail; > =20 > if (adc >=3D vdd || adc < LP5523_ADC_SHORTCIRC_LIM) > - pos +=3D sprintf(buf + pos, "LED %d FAIL\n", i); > + pos +=3D sprintf(buf + pos, "LED %d FAIL\n", > + led->chan_nr); > =20 > - lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + i, 0x00); > + lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr, > + 0x00); > =20 > /* Restore current */ > - lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + i, > - led->led_current); > + lp55xx_write(chip, LP5523_REG_LED_CURRENT_BASE + led->chan_nr, > + led->led_current); > led++; > } > if (pos =3D=3D 0) > --=20 > 2.37.3 --=20 People of Russia, stop Putin before his war on Ukraine escalates. --azLHFNyN32YCQGCU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCY1v2oQAKCRAw5/Bqldv6 8j8zAJ4583whUfrj47M9T7qQaBaALIaEiwCcDtOhDGdoDID3q8P0gLhCuvpq/8Y= =0oRS -----END PGP SIGNATURE----- --azLHFNyN32YCQGCU--