From patchwork Wed Dec 6 11:45:05 2023 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: 13481607 Received: from metis.whiteo.stw.pengutronix.de (metis.whiteo.stw.pengutronix.de [IPv6:2a0a:edc0:2:b01:1d::104]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C4D8D7D for ; Wed, 6 Dec 2023 03:48:48 -0800 (PST) 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 1rAqOQ-0007lD-At; Wed, 06 Dec 2023 12:48:42 +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 1rAqOO-00DwyO-Bd; Wed, 06 Dec 2023 12:48:40 +0100 Received: from ukl by ptz.office.stw.pengutronix.de with local (Exim 4.94.2) (envelope-from ) id 1rAqOO-00FR3r-2h; Wed, 06 Dec 2023 12:48:40 +0100 From: =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= To: Thierry Reding Cc: kernel@pengutronix.de, Kees Cook , "Gustavo A. R. Silva" , linux-pwm@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v4 111/115] pwm: Ensure a struct pwm has the same lifetime as its pwm_chip Date: Wed, 6 Dec 2023 12:45:05 +0100 Message-ID: <0ad4ff6c893412c7490decf188bafb4041e450c0.1701860672.git.u.kleine-koenig@pengutronix.de> X-Mailer: git-send-email 2.42.0 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=3372; i=u.kleine-koenig@pengutronix.de; h=from:subject:message-id; bh=zRXBPiuGDTSmT2iDUQspb6FQDRG35gXstVqIOwq/bQI=; b=owEBbQGS/pANAwAKAY+A+1h9Ev5OAcsmYgBlcF9loLszRsTIzoPcAEu4EyiogWYnYwoc+ksJM Bm2Nmb2KXmJATMEAAEKAB0WIQQ/gaxpOnoeWYmt/tOPgPtYfRL+TgUCZXBfZQAKCRCPgPtYfRL+ TgzpCACN0r3FBZSAmr5YeK6eMPWGuIIC95TXRnC7vM3spQzoUlQhx5X13L5RYM/5ozmoekzLiqM 1QzZyPskoVPsLX7LbdWWJfR04FMYpo54DDg79iftgUgAIaCfdGEkaZxtA+EUOmScycOxs97GgJn LgD/yhdlquuQyaOx05YFFcW7Ji1vTzQu6VubkPJWYKHDLgY3DL7HLQvj/Dyb4k/NlUvEdzCQkDf K7yc1eqfcMtylrovMMuvTv58rLBqwhgdFLrRsyH6sAObyUwGU6z3YgyhE5oBW50lNkeTzK78+5x ZwMqu30qwMILj9OdDtlHfXCEEYg5jrKKudkOf1f8x94SeAcr 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 ce6f4b397468..b3ba08aa0b14 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -200,15 +200,16 @@ static bool pwm_ops_check(const struct pwm_chip *chip) static void *pwmchip_priv(struct pwm_chip *chip) { - return (void *)chip + sizeof(*chip); + return (void *)chip + struct_size(chip, pwms, chip->npwm); } struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv) { struct pwm_chip *chip; size_t alloc_size; + unsigned int i; - alloc_size = size_add(sizeof(*chip), sizeof_priv); + alloc_size = size_add(struct_size(chip, pwms, npwm), sizeof_priv); chip = devm_kzalloc(parent, alloc_size, GFP_KERNEL); if (!chip) @@ -220,6 +221,13 @@ struct pwm_chip *devm_pwmchip_alloc(struct device *parent, unsigned int npwm, si 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(devm_pwmchip_alloc); @@ -236,7 +244,6 @@ EXPORT_SYMBOL_GPL(devm_pwmchip_alloc); */ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) { - unsigned int i; int ret; if (!chip || !chip->dev || !chip->ops || !chip->npwm) @@ -256,28 +263,16 @@ 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(&pwmchip_idr, 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)) @@ -307,8 +302,6 @@ void pwmchip_remove(struct pwm_chip *chip) idr_remove(&pwmchip_idr, 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 6a5b245e8951..eb91306ba28e 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -301,8 +301,8 @@ struct pwm_chip { /* only used internally by the PWM framework */ bool uses_pwmchip_alloc; - struct pwm_device *pwms; void *driver_data; + struct pwm_device pwms[] __counted_by(npwm); }; static inline struct device *pwmchip_parent(struct pwm_chip *chip)