linux-kernel - Re: [PATCH] net: qrtr: fix memory leak in qrtr_local

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Message-ID: <20210723122753.GA3739@thinkpad>
Date:   Fri, 23 Jul 2021 17:57:53 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Pavel Skripkin <paskripkin@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org,
        bjorn.andersson@...ymobile.com, courtney.cavin@...ymobile.com,
        linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        syzbot+35a511c72ea7356cdcf3@...kaller.appspotmail.com
Subject: Re: [PATCH] net: qrtr: fix memory leak in qrtr_local_enqueue

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@...kaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>

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

> ---
>  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
>