Re: [PATCH] wireless: wext: allocate space for NULL-terminationfor 32byte SSIDs

From: Johannes Berg
Date: Tue Dec 15 2009 - 05:06:05 EST


On Tue, 2009-12-15 at 11:03 +0100, Johannes Berg wrote:
> On Tue, 2009-12-15 at 01:43 -0800, David Miller wrote:
>
> > > The effect is that after a number of mode transistions (sometimes as few
> > > as two sufficed), the kernel will oops at very strange locations, mostly
> > > in something like __kmem_alloc().
> > >
> > > While the root cause turned out to be an issue with the wpa-supplicant
> > > which feeds the kernel driver with garbage, this occasion pointed out a
> > > bug in the wireless wext core when SSIDs with 32 byte lengths are passed
> > > from userspace. In this case, the string is not properly NULL-terminated
> > > which causes some other part to corrupt memory.

And, I forgot to mention, this is in fact not an issue or the "root
cause" of any issues -- it's completely intentional that wpa_supplicant
feeds the kernel with a random, valid, 32-byte SSID.

johannes

Attachment: signature.asc
Description: This is a digitally signed message part