[PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid

On Wed, Jan 27, 2016 at 02:45:26PM +0100, Arnd Bergmann wrote:

To ensure we get consistent error handling here, this changes the code
to only set rlen if we actually read data correctly, which also takes
care of the warning.

It may be a good idea to do the job better.  Looking at the code:

        struct hfa384x_rid_hdr rec;

        spin_lock_bh(&local->baplock);

        res = hfa384x_setup_bap(dev, BAP0, rid, 0);
        if (!res)
                res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));

The only thing which initialises any of "rec" is that function call.
The following lines are:

        if (le16_to_cpu(rec.len) == 0) {
                /* RID not available */
                res = -ENODATA;
        }

        rlen = (le16_to_cpu(rec.len) - 1) * 2;

So, why give the compiler a hard time as you're doing, why make the code
harder to read.  What's wrong with:

	spin_lock_bh(&local->baplock);

	res = hfa384x_setup_bap(dev, BAP0, rid, 0);
	if (res)
		goto unlock;

	res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
	if (res)
		goto unlock;

	if (le16_to_cpu(rec.len) == 0) {
		/* RID not available */
		res = -ENODATA;
		goto unlock;
	}

	rlen = (le16_to_cpu(rec.len) - 1) * 2;
	if (exact_len && rlen != len) {
		printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch: rid=0x%04x, len=%d (expected %d)\n",
		       dev->name, rid, rlen, len);
		res = -ENODATA;
		goto unlock;
	}

	res = hfa384x_from_bap(dev, BAP0, buf, len);
unlock:
	spin_unlock_bh(&local->baplock);

?

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