netdev - Re: [PATCH net] net/packet: move reference count in packet

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Date: Fri, 1 Dec 2023 09:35:49 +0000
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Daniel Borkmann <daniel@...earbox.net>
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	netdev@...r.kernel.org,
	"The UK's National Cyber Security Centre (NCSC)" <security@...c.gov.uk>,
	stable <stable@...nel.org>
Subject: Re: [PATCH net] net/packet: move reference count in packet_sock to
 64 bits

On Fri, Dec 01, 2023 at 10:19:35AM +0100, Daniel Borkmann wrote:
> On 11/30/23 4:15 PM, Willem de Bruijn wrote:
> > Daniel Borkmann wrote:
> > > On 11/30/23 3:20 PM, Greg Kroah-Hartman wrote:
> > > > In some potential instances the reference count on struct packet_sock
> > > > could be saturated and cause overflows which gets the kernel a bit
> > > > confused.  To prevent this, move to a 64bit atomic reference count to
> > > > prevent the possibility of this type of overflow.
> > > > 
> > > > Because we can not handle saturation, using refcount_t is not possible
> > > > in this place.  Maybe someday in the future if it changes could it be
> > > > used.
> > > > 
> > > > Original version from Daniel after I did it wrong, I've provided a
> > > > changelog.
> > > > 
> > > > Reported-by: "The UK's National Cyber Security Centre (NCSC)" <security@...c.gov.uk>
> > > > Cc: stable <stable@...nel.org>
> > > > Cc: Daniel Borkmann <daniel@...earbox.net>
> > > > Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > > 
> > > Thanks!
> > > 
> > > Acked-by: Daniel Borkmann <daniel@...earbox.net>
> > 
> > Acked-by: Willem de Bruijn <willemb@...gle.com>
> 
> There was feedback from Linus that switching to atomic_long_t is better
> choice so that it doesn't penalize 32-bit architectures. Will post a v2
> today.

Thanks, makes sense to do it that way.

greg k-h