Re: Bluetooth regression breaking BT connection for all 2.0 and older devices in 5.0.15+, 5.1.x and master

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Jun 10, 2019 at 03:31:55PM +0200, Hans de Goede wrote:
> Hi All,
> 
> First of all this is a known issue and it seems a fix is in the works,
> but what I do not understand is why the commit causing this has not
> simply been reverted until the fix is done, esp. for the 5.0.x
> stable series where this was introduced in 5.0.15.
> 
> The problem I'm talking about is commit d5bb334a8e17 ("Bluetooth: Align
> minimum encryption key size for LE and BR/EDR connections"):
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5bb334a8e171b262e48f378bd2096c0ea458265
> basically completely breaking all somewhat older (and some current cheap
> no-name) bluetooth devices:
> 
> A revert of this was first proposed on May 22nd:
> https://lore.kernel.org/netdev/CA+E=qVfopSA90vG2Kkh+XzdYdNn=M-hJN_AptW=R+B5v3HB9eA@mail.gmail.com/T/
> We are 18 days further now and this problem still exists, including in the
> 5.0.15+ and 5.1.x stable kernels.
> 
> A solution has been suggested: https://lore.kernel.org/linux-bluetooth/20190522070540.48895-1-marcel@holtmann.org/T/#u
> and at least the Fedora 5.1.4+ kernels now carry this as a temporary fix,
> but as of today I do not see a fix nor a revert in Torvald's tree yet and
> neither does there seem to be any fix in the 5.0.x and 5.1.x stable series.
> 
> In the mean time we are getting a lot of bug reports about this:
> https://bugzilla.kernel.org/show_bug.cgi?id=203643
> https://bugzilla.redhat.com/show_bug.cgi?id=1711468
> https://bugzilla.redhat.com/show_bug.cgi?id=1713871
> https://bugzilla.redhat.com/show_bug.cgi?id=1713980
> 
> And some reporters:
> https://bugzilla.redhat.com/show_bug.cgi?id=1713871#c4
> Are indicating that the Fedora kernels with the workaround included
> still do not work...
> 
> As such I would like to suggest that we just revert the troublesome
> commit for now and re-add it when we have a proper fix.

I've now reverted this as it does not seem to be going anywhere anytime
soon.  After the mess gets sorted out in Linus's tree, if someone could
send stable@vger the commit ids that should be applied, I will be glad
to do so.

thanks,

greg k-h