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Tue, 02 Mar 2021 15:44:08 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 3174E10002A; Tue, 2 Mar 2021 15:44:07 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node3.st.com [10.75.127.6]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 21D32241615; Tue, 2 Mar 2021 15:44:07 +0100 (CET) Received: from localhost (10.75.127.51) by SFHDAG2NODE3.st.com (10.75.127.6) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 2 Mar 2021 15:44:06 +0100 From: Fabrice Gasnier To: , CC: , , , , , , , , Subject: [PATCH] counter: stm32-timer-cnt: fix ceiling write max value Date: Tue, 2 Mar 2021 15:43:55 +0100 Message-ID: <1614696235-24088-1-git-send-email-fabrice.gasnier@foss.st.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.75.127.51] X-ClientProxiedBy: SFHDAG2NODE1.st.com (10.75.127.4) To SFHDAG2NODE3.st.com (10.75.127.6) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369, 18.0.761 definitions=2021-03-02_06:2021-03-01, 2021-03-02 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210302_144508_625157_E77AA447 X-CRM114-Status: GOOD ( 14.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The ceiling value isn't checked before writing it into registers. The user could write a value higher than the counter resolution (e.g. 16 or 32 bits indicated by max_arr). This makes most significant bits to be truncated. Fix it by checking the max_arr to report a range error [1] to the user. Fixes: ad29937e206f ("counter: Add STM32 Timer quadrature encoder") [1] https://lkml.org/lkml/2021/2/12/358 Signed-off-by: Fabrice Gasnier Acked-by: William Breathitt Gray --- drivers/counter/stm32-timer-cnt.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c index ef2a974..2cf0c05 100644 --- a/drivers/counter/stm32-timer-cnt.c +++ b/drivers/counter/stm32-timer-cnt.c @@ -32,6 +32,7 @@ struct stm32_timer_cnt { struct regmap *regmap; struct clk *clk; u32 ceiling; + u32 max_arr; bool enabled; struct stm32_timer_regs bak; }; @@ -185,6 +186,9 @@ static ssize_t stm32_count_ceiling_write(struct counter_device *counter, if (ret) return ret; + if (ceiling > priv->max_arr) + return -ERANGE; + /* TIMx_ARR register shouldn't be buffered (ARPE=0) */ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0); regmap_write(priv->regmap, TIM_ARR, ceiling); @@ -360,6 +364,7 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev) priv->regmap = ddata->regmap; priv->clk = ddata->clk; priv->ceiling = ddata->max_arr; + priv->max_arr = ddata->max_arr; priv->counter.name = dev_name(dev); priv->counter.parent = dev;