From 9b024201693e397441668cca0d2df7055fe572eb Mon Sep 17 00:00:00 2001
From: Vadim Pasternak <vadimp@nvidia.com>
Date: Mon, 27 Sep 2021 17:22:13 +0300
Subject: [PATCH] platform/mellanox: mlxreg-io: Fix argument base in kstrtou32() call
Git-commit: 9b024201693e397441668cca0d2df7055fe572eb
Patch-mainline: v5.15-rc6
References: git-fixes stable-5.14.14

Change kstrtou32() argument 'base' to be zero instead of 'len'.
It works by chance for setting one bit value, but it is not supposed to
work in case value passed to mlxreg_io_attr_store() is greater than 1.

It works for example, for:
echo 1 > /sys/devices/platform/mlxplat/mlxreg-io/hwmon/.../jtag_enable
But it will fail for:
echo n > /sys/devices/platform/mlxplat/mlxreg-io/hwmon/.../jtag_enable,
where n > 1.

The flow for input buffer conversion is as below:
_kstrtoull(const char *s, unsigned int base, unsigned long long *res)
Calls: 
rv = _parse_integer(s, base, &_res);

For the second case, where n > 1:
- _parse_integer() converts 's' to 'val'.
  For n=2, 'len' is set to 2 (string buffer is 0x32 0x0a), for n=3
  'len' is set to 3 (string buffer 0x33 0x0a), etcetera.
- 'base' is equal or greater then '2' (length of input buffer).

As a result, _parse_integer() exits with result zero (rv):
	rv = 0;
	while (1) {
		...
		if (val >= base)-> (2 >= 2)
			break;
		...
		rv++;
		...
	}

And _kstrtoull() in their turn will fail:
	if (rv == 0)
		return -EINVAL;

Fixes: 5ec4a8ace06c ("platform/mellanox: Introduce support for Mellanox register access driver")
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20210927142214.2613929-2-vadimp@nvidia.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/platform/mellanox/mlxreg-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/mellanox/mlxreg-io.c b/drivers/platform/mellanox/mlxreg-io.c
index 7646708d57e4..a023ec02126b 100644
--- a/drivers/platform/mellanox/mlxreg-io.c
+++ b/drivers/platform/mellanox/mlxreg-io.c
@@ -141,7 +141,7 @@ mlxreg_io_attr_store(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 
 	/* Convert buffer to input value. */
-	ret = kstrtou32(buf, len, &input_val);
+	ret = kstrtou32(buf, 0, &input_val);
 	if (ret)
 		return ret;
 
-- 
2.26.2