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Fri, 26 Nov 2021 17:57:58 +0100 (CET) Message-ID: <8e5493ac-dd05-9bad-c9ae-169114e0fdcf@csgroup.eu> Date: Fri, 26 Nov 2021 17:57:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH v2] w1: Misuse of get_user()/put_user() reported by sparse Content-Language: fr-FR To: Greg Kroah-Hartman References: <926b572075a26835f4e39d05710cd1b75fd4d5a4.1637945194.git.christophe.leroy@csgroup.eu> From: Christophe Leroy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Evgeniy Polyakov , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kernel test robot Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 26/11/2021 à 17:54, Greg Kroah-Hartman a écrit : > On Fri, Nov 26, 2021 at 05:47:58PM +0100, Christophe Leroy wrote: >> sparse warnings: (new ones prefixed by >>) >>>> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected char [noderef] __user *_pu_addr @@ got char *buf @@ >> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: expected char [noderef] __user *_pu_addr >> drivers/w1/slaves/w1_ds28e04.c:342:13: sparse: got char *buf >>>> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected char const [noderef] __user *_gu_addr @@ got char const *buf @@ >> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: expected char const [noderef] __user *_gu_addr >> drivers/w1/slaves/w1_ds28e04.c:356:13: sparse: got char const *buf >> >> The buffer buf is a failsafe buffer in kernel space, it's not user >> memory hence doesn't deserve the use of get_user() or put_user(). >> >> Access 'buf' content directly. >> >> Reported-by: kernel test robot >> Link: https://lore.kernel.org/lkml/202111190526.K5vb7NWC-lkp@intel.com/T/ >> Signed-off-by: Christophe Leroy >> --- >> v2: Use sysfs_emit() and kstrtobool() >> --- >> drivers/w1/slaves/w1_ds28e04.c | 25 +++---------------------- >> 1 file changed, 3 insertions(+), 22 deletions(-) >> >> diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c >> index e4f336111edc..98f80f412cfd 100644 >> --- a/drivers/w1/slaves/w1_ds28e04.c >> +++ b/drivers/w1/slaves/w1_ds28e04.c >> @@ -32,7 +32,7 @@ static int w1_strong_pullup = 1; >> module_param_named(strong_pullup, w1_strong_pullup, int, 0); >> >> /* enable/disable CRC checking on DS28E04-100 memory accesses */ >> -static char w1_enable_crccheck = 1; >> +static bool w1_enable_crccheck = true; >> >> #define W1_EEPROM_SIZE 512 >> #define W1_PAGE_COUNT 16 >> @@ -339,32 +339,13 @@ static BIN_ATTR_RW(pio, 1); >> static ssize_t crccheck_show(struct device *dev, struct device_attribute *attr, >> char *buf) >> { >> - if (put_user(w1_enable_crccheck + 0x30, buf)) >> - return -EFAULT; >> - >> - return sizeof(w1_enable_crccheck); >> + return sysfs_emit(buf, "%d\n", w1_enable_crccheck); >> } >> >> static ssize_t crccheck_store(struct device *dev, struct device_attribute *attr, >> const char *buf, size_t count) >> { >> - char val; >> - >> - if (count != 1 || !buf) >> - return -EINVAL; >> - >> - if (get_user(val, buf)) >> - return -EFAULT; >> - >> - /* convert to decimal */ >> - val = val - 0x30; >> - if (val != 0 && val != 1) >> - return -EINVAL; >> - >> - /* set the new value */ >> - w1_enable_crccheck = val; >> - >> - return sizeof(w1_enable_crccheck); >> + return kstrtobool(buf, &w1_enable_crccheck) ? : count; > > Please spell this line out, using ? : is unreadable at times. > You prefer something like: int err = kstrtobool(buf, &w1_enable_crccheck); return err ? err : count; Or int err = kstrtobool(buf, &w1_enable_crccheck); if (err) return err; return count; ?