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Date:   Fri, 23 Jul 2021 18:08:05 +0300
From:   Pavel Skripkin <paskripkin@gmail.com>
To:     Manivannan Sadhasivam <mani@kernel.org>
Cc:     davem@davemloft.net, kuba@kernel.org,
        bjorn.andersson@sonymobile.com, courtney.cavin@sonymobile.com,
        linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
Subject: Re: [PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue
Message-ID: <20210723180805.0f961fbc@gmail.com>
In-Reply-To: <20210723122753.GA3739@thinkpad>
References: <20210722161625.6956-1-paskripkin@gmail.com>
        <20210723122753.GA3739@thinkpad>
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On Fri, 23 Jul 2021 17:57:53 +0530
Manivannan Sadhasivam <mani@kernel.org> wrote:

> On Thu, Jul 22, 2021 at 07:16:25PM +0300, Pavel Skripkin wrote:
> > Syzbot reported memory leak in qrtr. The problem was in unputted
> > struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
> > which takes sock reference if port was found. Then there is the
> > following check:
> > 
> > if (!ipc || &ipc->sk == skb->sk) {
> > 	...
> > 	return -ENODEV;
> > }
> > 
> > Since we should drop the reference before returning from this
> > function and ipc can be non-NULL inside this if, we should add
> > qrtr_port_put() inside this if.
> > 
> > Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
> > Reported-and-tested-by:
> > syzbot+35a511c72ea7356cdcf3@syzkaller.appspotmail.com
> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> 
> Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
> 
> It'd be good if this patch can be extended to fix one more corner
> case here:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/qrtr/qrtr.c#n522
> 
> Thanks,
> Mani

Hi, Manivannan!

I will fix leak there too in v2, thank you! 


With regards,
Pavel Skripkin

> 
> > ---
> >  net/qrtr/qrtr.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> > index e6f4a6202f82..d5ce428d0b25 100644
> > --- a/net/qrtr/qrtr.c
> > +++ b/net/qrtr/qrtr.c
> > @@ -839,6 +839,8 @@ static int qrtr_local_enqueue(struct qrtr_node
> > *node, struct sk_buff *skb, 
> >  	ipc = qrtr_port_lookup(to->sq_port);
> >  	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self
> > */
> > +		if (ipc)
> > +			qrtr_port_put(ipc);
> >  		kfree_skb(skb);
> >  		return -ENODEV;
> >  	}
> > -- 
> > 2.32.0
> >