Re: [PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid

From: Russell King - ARM Linux
Date: Wed Jan 27 2016 - 14:26:38 EST


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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