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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4409d1e19e1sm120832795e9.0.2025.04.27.04.17.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Apr 2025 04:17:06 -0700 (PDT) Date: Sun, 27 Apr 2025 12:17:04 +0100 From: David Laight To: Lifeng Zheng Cc: , , , , , , , , , , Subject: Re: [PATCH 1/4] PM / devfreq: governor: Replace sscanf() with kstrtoul() in set_freq_store() Message-ID: <20250427121704.51e3af2a@pumpkin> In-Reply-To: <20250421030020.3108405-2-zhenglifeng1@huawei.com> References: <20250421030020.3108405-1-zhenglifeng1@huawei.com> <20250421030020.3108405-2-zhenglifeng1@huawei.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 21 Apr 2025 11:00:17 +0800 Lifeng Zheng wrote: > Replace sscanf() with kstrtoul() in set_freq_store() and check the result > to avoid invalid input. Isn't this a UAPI change? The sscanf() version will ignore trailing characters. In this case it is actually likely that value might have a trailing "Hz". David > > Signed-off-by: Lifeng Zheng > --- > drivers/devfreq/governor_userspace.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c > index d1aa6806b683..175de0c0b50e 100644 > --- a/drivers/devfreq/governor_userspace.c > +++ b/drivers/devfreq/governor_userspace.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -39,10 +40,13 @@ static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr, > unsigned long wanted; > int err = 0; > > + err = kstrtoul(buf, 0, &wanted); > + if (err) > + return err; > + > mutex_lock(&devfreq->lock); > data = devfreq->governor_data; > > - sscanf(buf, "%lu", &wanted); > data->user_frequency = wanted; > data->valid = true; > err = update_devfreq(devfreq);