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Date:   Thu, 5 Oct 2023 10:35:56 +0300
From:   Andrew Kanner <andrew.kanner@gmail.com>
To:     Daniel Borkmann <daniel@iogearbox.net>
Cc:     bjorn@kernel.org, magnus.karlsson@intel.com,
        maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, aleksander.lobakin@intel.com,
        xuanzhuo@linux.alibaba.com, ast@kernel.org, hawk@kernel.org,
        john.fastabend@gmail.com,
        linux-kernel-mentees@lists.linuxfoundation.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com
Subject: Re: [PATCH net-next v2] net/xdp: fix zero-size allocation warning in
 xskq_create()
References: <20231002222939.1519-1-andrew.kanner@gmail.com>
 <2f5abbf8-8d50-3deb-19cd-9bfd654e1ceb@iogearbox.net>
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On Thu, Oct 05, 2023 at 12:49:23AM +0200, Daniel Borkmann wrote:
[...]
> > 
> > Reported-and-tested-by: syzbot+fae676d3cf469331fc89@syzkaller.appspotmail.com
> > Closes: https://lore.kernel.org/all/000000000000c84b4705fb31741e@google.com/T/
> > Link: https://syzkaller.appspot.com/bug?extid=fae676d3cf469331fc89
> > Fixes: 9f78bf330a66 ("xsk: support use vaddr as ring")
> > Signed-off-by: Andrew Kanner <andrew.kanner@gmail.com>
> 
> I guess also:
> 
> Reported-by: syzbot+b132693e925cbbd89e26@syzkaller.appspotmail.com
> 
> Moreover, this fix is needed in bpf/net tree (as opposed to *-next tree), right?
>

Seems, so - I will check.

> >   net/xdp/xsk_queue.c | 3 +++
> >   1 file changed, 3 insertions(+)
> > 
> > diff --git a/net/xdp/xsk_queue.c b/net/xdp/xsk_queue.c
> > index f8905400ee07..b03d1bfb6978 100644
> > --- a/net/xdp/xsk_queue.c
> > +++ b/net/xdp/xsk_queue.c
> > @@ -34,6 +34,9 @@ struct xsk_queue *xskq_create(u32 nentries, bool umem_queue)
> >   	q->ring_mask = nentries - 1;
> >   	size = xskq_get_ring_size(q, umem_queue);
> > +	if (unlikely(size == SIZE_MAX))
> > +		return NULL;
> 
> Doesn't this leak q here ?
> 
> >   	size = PAGE_ALIGN(size);
> >   	q->ring = vmalloc_user(size);
> > 
> 

It is.
Thanks, Daniel, I will fix it in v3. 

pw-bot: cr

--
Andrew Kanner