scsi: target: tcmu: Replace strlcpy() with strscpy()

strlcpy() reads the entire source buffer first.  This read may exceed the
destination size limit.  This is both inefficient and can lead to linear
read overflows if a source string is not NUL-terminated [1].  In an effort
to remove strlcpy() completely [2], replace strlcpy() here with strscpy().

No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] KSPP#89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20230621030033.3800351-3-azeemshaikh38@gmail.com
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: azeemshaikh38

drivers/target/target_core_user.c

@@ -2820,14 +2820,14 @@ static ssize_t tcmu_dev_config_store(struct config_item *item, const char *page,
 			pr_err("Unable to reconfigure device\n");
 			return ret;
 		}
-		strlcpy(udev->dev_config, page, TCMU_CONFIG_LEN);
+		strscpy(udev->dev_config, page, TCMU_CONFIG_LEN);
 
 		ret = tcmu_update_uio_info(udev);
 		if (ret)
 			return ret;
 		return count;
 	}
-	strlcpy(udev->dev_config, page, TCMU_CONFIG_LEN);
+	strscpy(udev->dev_config, page, TCMU_CONFIG_LEN);
 
 	return count;
 }