On Thu, 2021-02-11 at 10:11 +0300, Dan Carpenter wrote:

On Wed, Feb 10, 2021 at 02:28:54PM -0800, Drew Fustini wrote:

quoted

+	ret = strncpy_from_user(buf, user_buf, PINMUX_MAX_NAME * 2);
+	if (ret < 0) {
+		dev_err(pctldev->dev, "failed to copy buffer from userspace");
+		goto free_gname;
+	}
+	buf[len-1] = '\0';
+
+	ret = sscanf(buf, "%s %s", fname, gname);
+	if (ret != 2) {
+		dev_err(pctldev->dev, "expected format: <function-name> <group-name>");
+		goto free_gname;

We need a "ret = -EINVAL;" before the goto.  sscanf doesn't return error
codes.  Normally we would write it like so:

	if (sscanf(buf, "%s %s", fname, gname) != 2) {
		dev_err(pctldev->dev, "expected format: <function-name> <group-name>");
		ret = -EINVAL;
		goto free_gname;
	}

I'm going to write a Smatch check for this today.

It's a pretty frequently used style:

$ git grep -P '\w+\s*=\s+sscanf\b' | wc -l
327

A grep with -A5 seems to show most use some additional error assignment
when checking the return value.

$ git grep -P -A5 '\w+\s*=\s+sscanf\b' | grep -P '(?:return|=)\s*\-E' | wc -l
174