w1: Misuse of get_user()/put_user() reported by sparse

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.

Link: https://lore.kernel.org/lkml/202111190526.K5vb7NWC-lkp@intel.com/T/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/d14ed8d71ad4372e6839ae427f91441d3ba0e94d.1637946316.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c
index e4f3361..6cef6e2 100644 (file)
--- 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 +339,18 @@ 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;
+       int err = kstrtobool(buf, &w1_enable_crccheck);
 
-       if (get_user(val, buf))
-               return -EFAULT;
+       if (err)
+               return err;
 
-       /* 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 count;
 }
 
 static DEVICE_ATTR_RW(crccheck);