netdev - Re: [PATCH v2] net: qrtr: fix memory leaks

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Date:   Fri, 23 Jul 2021 21:13:50 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Pavel Skripkin <paskripkin@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, loic.poulain@...aro.org,
        bjorn.andersson@...aro.org, xiyou.wangcong@...il.com,
        edumazet@...gle.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+35a511c72ea7356cdcf3@...kaller.appspotmail.com
Subject: Re: [PATCH v2] net: qrtr: fix memory leaks

On Fri, Jul 23, 2021 at 06:31:32PM +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.
> 
> The similar corner case is in qrtr_endpoint_post() as Manivannan
> reported. In case of sock_queue_rcv_skb() failure we need to put
> port reference to avoid leaking struct sock pointer.
> 
> Fixes: e04df98adf7d ("net: qrtr: Remove receive worker")
> Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
> Reported-and-tested-by: syzbot+35a511c72ea7356cdcf3@...kaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>

Reviewed-by: Manivannan Sadhasivam <mani@...nel.org>

Thanks,
Mani

> ---
> 
> Changes in v2:
> 	Added missing qrtr_port_put() in qrtr_endpoint_post() as Manivannan
> 	reported.
> 
> ---
>  net/qrtr/qrtr.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
> index b34358282f37..a8b2c9b21a8d 100644
> --- a/net/qrtr/qrtr.c
> +++ b/net/qrtr/qrtr.c
> @@ -514,8 +514,10 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
>  		if (!ipc)
>  			goto err;
>  
> -		if (sock_queue_rcv_skb(&ipc->sk, skb))
> +		if (sock_queue_rcv_skb(&ipc->sk, skb)) {
> +			qrtr_port_put(ipc);
>  			goto err;
> +		}
>  
>  		qrtr_port_put(ipc);
>  	}
> @@ -850,6 +852,8 @@ 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
>