[PATCH 5.4 235/320] w1: Misuse of get_user()/put_user() reported by sparse

Greg Kroah-Hartman
2022-01-24T20:17:04Z

From: Christophe Leroy <christophe.leroy@csgroup.eu>

[ Upstream commit 33dc3e3e99e626ce51f462d883b05856c6c30b1d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/w1/slaves/w1_ds28e04.c | 26 ++++++--------------------
1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c
index 8a640f1590784..06a9966f8c933 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 +339,18 @@ 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);
--
2.34.1