From patchwork Wed Feb 14 09:33:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= X-Patchwork-Id: 13556240 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [185.203.201.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EF6D168AF for ; Wed, 14 Feb 2024 09:53:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.203.201.7 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707904417; cv=none; b=K0vV8WCU0C+DjbV34sERJm52zS60FhNOO0PsfJXL2XH4Pc6jrSeQoFv4lPSTjsncJRaWbFtZPm7wDTVVJQz/dcmEJFXML3xlgs/vf17jcvPLB+TsDRDNV1Rs83ZULkes97U28cJ0VG4nq+dAN5Jeg5+TcXl+KX2BWpazw3ug7sk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707904417; c=relaxed/simple; bh=Kw8zUn6zUlRDspKiD00c84AIO4QqNIF1NhJzUFD68Ko=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=d7qYFMj3pox7517GFQI6AwdgznlBY/EJJfXoBBip+vKN20FdSLt4P+n01dNxNAkjxCktpTkhbu2nvCM4USNgdf8TYdnpwZaaw6klzw55yxJbMsNhl3RnFW8MHkQ3gIq8XGooog4IuFkCudWeMCCYGUYksO4E2VbTblEGUjOwzmw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; arc=none smtp.client-ip=185.203.201.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1raBfB-0006Kf-Qk; Wed, 14 Feb 2024 10:34:45 +0100 Received: from [2a0a:edc0:0:900:1d::77] (helo=ptz.office.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1raBf8-000fIu-Lo; Wed, 14 Feb 2024 10:34:42 +0100 Received: from ukl by ptz.office.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1raBf8-004YAl-1w; Wed, 14 Feb 2024 10:34:42 +0100 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Kees Cook , linux-pwm@vger.kernel.org Cc: "Gustavo A. R. Silva" , kernel@pengutronix.de, linux-hardening@vger.kernel.org Subject: [PATCH v6 162/164] pwm: Ensure a struct pwm has the same lifetime as its pwm_chip Date: Wed, 14 Feb 2024 10:33:29 +0100 Message-ID: <3eb4ed957bf37faf67a978816c4bf619176d8545.1707900770.git.u.kleine-koenig@pengutronix.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3500; i=u.kleine-koenig@pengutronix.de; h=from:subject:message-id; bh=Kw8zUn6zUlRDspKiD00c84AIO4QqNIF1NhJzUFD68Ko=; b=owGbwMvMwMXY3/A7olbonx/jabUkhtQznSzm0wP+cvveVy+aJtnFm1Z+Ujlhxc83Huc29FbNe /81S6ypk9GYhYGRi0FWTJHFvnFNplWVXGTn2n+XYQaxMoFMYeDiFICJbGXiYJhlEXhQ4b/YtJqE I3I2lrKqD0+I6SjMNj2kc0gpcGedmIF0PG8M15RPSqftjuiUy2rtmH8lcIu1w16lMoYdSjzcv/4 e0fOSXZGlz3Lswa/8y7y62V3J/VGfGFavOnt+nzLnVjXXzFyBINZVSZWF1Zl3BH5vtmvQDy332a Gp1nYraVpg0bwaA7sJvJwJdvxPFgg3PX/z0XruVGsVvZunZ5yKWqJ50qR1/uaroc26fAtebLD/0 hITM5MvoeP9hEqRf2J51zzkL84LNeFx+GBtN62xyynnQvj8HXqMgqEfn39Y/c6a5bT1YvuvH/vm 3G3bJO0Q8PFa8H4eSaFFDL9T5jPKJH9Zdt6x8FTYhx8PAA== X-Developer-Key: i=u.kleine-koenig@pengutronix.de; a=openpgp; fpr=0D2511F322BFAB1C1580266BE2DCDD9132669BD6 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.whiteo.stw.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-hardening@vger.kernel.org It's required to not free the memory underlying a requested PWM while a consumer still has a reference to it. While currently a pwm_chip doesn't life long enough in all cases, linking the struct pwm to the pwm_chip results in the right lifetime as soon as the pwmchip is living long enough. This happens with the following commits. Note this is a breaking change for all pwm drivers that don't use pwmchip_alloc(). Reviewed-by: Gustavo A. R. Silva # for struct_size() and __counted_by() Signed-off-by: Uwe Kleine-König --- drivers/pwm/core.c | 27 ++++++++++----------------- include/linux/pwm.h | 2 +- 2 files changed, 11 insertions(+), 18 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index cae93ccc32ed..c8303da06b62 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -458,7 +458,7 @@ EXPORT_SYMBOL_GPL(of_pwm_single_xlate); static void *pwmchip_priv(struct pwm_chip *chip) { - return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN); + return (void *)chip + ALIGN(struct_size(chip, pwms, chip->npwm), PWMCHIP_ALIGN); } /* This is the counterpart to pwmchip_alloc */ @@ -472,8 +472,9 @@ struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t { struct pwm_chip *chip; size_t alloc_size; + unsigned int i; - alloc_size = size_add(ALIGN(sizeof(*chip), PWMCHIP_ALIGN), sizeof_priv); + alloc_size = size_add(ALIGN(struct_size(chip, pwms, npwm), PWMCHIP_ALIGN), sizeof_priv); chip = kzalloc(alloc_size, GFP_KERNEL); if (!chip) @@ -485,6 +486,13 @@ struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t pwmchip_set_drvdata(chip, pwmchip_priv(chip)); + for (i = 0; i < chip->npwm; i++) { + struct pwm_device *pwm = &chip->pwms[i]; + + pwm->chip = chip; + pwm->hwpwm = i; + } + return chip; } EXPORT_SYMBOL_GPL(pwmchip_alloc); @@ -556,7 +564,6 @@ static bool pwm_ops_check(const struct pwm_chip *chip) */ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) { - unsigned int i; int ret; if (!chip || !pwmchip_parent(chip) || !chip->ops || !chip->npwm) @@ -576,28 +583,16 @@ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) chip->owner = owner; - chip->pwms = kcalloc(chip->npwm, sizeof(*chip->pwms), GFP_KERNEL); - if (!chip->pwms) - return -ENOMEM; - mutex_lock(&pwm_lock); ret = idr_alloc(&pwm_chips, chip, 0, 0, GFP_KERNEL); if (ret < 0) { mutex_unlock(&pwm_lock); - kfree(chip->pwms); return ret; } chip->id = ret; - for (i = 0; i < chip->npwm; i++) { - struct pwm_device *pwm = &chip->pwms[i]; - - pwm->chip = chip; - pwm->hwpwm = i; - } - mutex_unlock(&pwm_lock); if (IS_ENABLED(CONFIG_OF)) @@ -627,8 +622,6 @@ void pwmchip_remove(struct pwm_chip *chip) idr_remove(&pwm_chips, chip->id); mutex_unlock(&pwm_lock); - - kfree(chip->pwms); } EXPORT_SYMBOL_GPL(pwmchip_remove); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 94a642a88817..fbd8f5db938a 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -290,7 +290,7 @@ struct pwm_chip { /* only used internally by the PWM framework */ bool uses_pwmchip_alloc; void *driver_data; - struct pwm_device *pwms; + struct pwm_device pwms[] __counted_by(npwm); }; static inline struct device *pwmchip_parent(const struct pwm_chip *chip)