Re: Patch "vsock/virtio: fix potential unbounded skb queue" has been added to the 6.6-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 16, 2026 at 10:36:43AM +0200, Stefano Garzarella wrote:
> On Tue, 16 Jun 2026 at 10:00, Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Tue, Jun 16, 2026 at 09:52:32AM +0200, Stefano Garzarella wrote:
> > > On Tue, Jun 16, 2026 at 10:17:31AM +0530, Greg KH wrote:
> > > > On Thu, May 21, 2026 at 03:15:54PM +0200, Stefano Garzarella wrote:
> > > > > On Sun, May 17, 2026 at 09:33:06AM -0400, Sasha Levin wrote:
> > > > > > > > What's the status of that fix?
> > > > > > >
> > > > > > > Stefano posted v3 and is working on v4.
> > > > > > >
> > > > > > > >  Should it be reverted elsewhere?
> > > > > > >
> > > > > > > Donnu. With the change we have no DoS but the socket gets silently
> > > > > > > broken.  Eric felt given the brokenness is upstream already it's better
> > > > > > > to work on a fix on top, not revert.
> > > > > >
> > > > > > Dropped from the 6.6, 6.12, 6.18, and 7.0 queues. We'll pick up Stefano's
> > > > > > follow-up once it lands upstream.
> > > > >
> > > > > FYI v4 is now merged in the net tree, so I guess they will land upstream
> > > > > soon. I CCed stable on both patches:
> > > > >
> > > > > a4f0b001782b ("vsock/virtio: reset connection on receiving queue overflow")
> > > > > c6087c5aaad6 ("vsock/virtio: fix skb overhead accounting to preserve full
> > > > > buf_alloc")
> > > > >
> > > > > Both are related, but the second is the main fix of this patch.
> > > >
> > > > THe second one doesn't apply at all :(
> > > >
> > >
> > > The second one is the fix of the patch originally added to stable queue by
> > > this thread, so should be applied on top of it (commit 059b7dbd20a6
> > > ("vsock/virtio: fix potential unbounded skb queue")).
> > >
> > > I'm working on improving memory management, but for now I think it makes
> > > sense to backport all three to the stable branches.
> > >
> > > So, in summary:
> > > 059b7dbd20a6 ("vsock/virtio: fix potential unbounded skb queue")
> > > a4f0b001782b ("vsock/virtio: reset connection on receiving queue overflow")
> > > c6087c5aaad6 ("vsock/virtio: fix skb overhead accounting to preserve full buf_alloc")
> >
> > Again, this last one fails to apply everywhere :(
> 
> Again, c6087c5aaad6 depends on 059b7dbd20a6 (as also indicated by the 
> Fixes tag in the patch description).
> 
> I don't know what you meant with "everywhere", but I just run `git 
> cherry-pick 059b7dbd20a6 c6087c5aaad6` on linux-6.12.y, linux-6.18.y, 
> and linux-7.0.y without any issue.

Sorry, I was just searching for the short-id, which is in commits
already in those trees.  The real commit worked, sorry for the
confusion.

> On linux-6.6.y it's failing because we are missing zero-copy support in 
> AF_VSOCK. So, I guess we didn't backport commit 45ca7e9f0730 
> ("vsock/virtio: fix `rx_bytes` accounting for stream sockets") because 
> there were conflicts.  That patch is needed to apply commit 059b7dbd20a6 
> ("vsock/virtio: fix potential unbounded skb queue") cleanly.

That commit does not backport cleanly to 6.6.y, so I still need a patch
series for that tree.

thanks,

greg k-h