linux-kernel - Re: [PATCH] ISDN, Gigaset: Fix memory leak in do_disconnect

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Message-ID: <4D1A2185.2010700@imap.cc>
Date:	Tue, 28 Dec 2010 18:42:29 +0100
From:	Tilman Schmidt <tilman@...p.cc>
To:	Jesper Juhl <jj@...osbits.net>
CC:	gigaset307x-common@...ts.sourceforge.net,
	Hansjoerg Lipp <hjlipp@....de>,
	Karsten Keil <isdn@...ux-pingi.de>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ISDN, Gigaset: Fix memory leak in do_disconnect_req()

Quite correct. Thanks for finding and fixing this.

Am 26.12.2010 20:59 schrieb Jesper Juhl:
> Hi,
> 
> In drivers/isdn/gigaset/capi.c::do_disconnect_req() we will leak the 
> memory allocated (with kmalloc) to 'b3cmsg' if the call to alloc_skb() 
> fails.
> 
> ...
> 		b3cmsg = kmalloc(sizeof(*b3cmsg), GFP_KERNEL);
> 	allocation here ------^
> 		if (!b3cmsg) {
> 			dev_err(cs->dev, "%s: out of memory\n", __func__);
> 			send_conf(iif, ap, skb, CAPI_MSGOSRESOURCEERR);
> 			return;
> 		}
> 		capi_cmsg_header(b3cmsg, ap->id, CAPI_DISCONNECT_B3, CAPI_IND,
> 				 ap->nextMessageNumber++,
> 				 cmsg->adr.adrPLCI | (1 << 16));
> 		b3cmsg->Reason_B3 = CapiProtocolErrorLayer1;
> 		b3skb = alloc_skb(CAPI_DISCONNECT_B3_IND_BASELEN, GFP_KERNEL);
> 		if (b3skb == NULL) {
> 			dev_err(cs->dev, "%s: out of memory\n", __func__);
> 			send_conf(iif, ap, skb, CAPI_MSGOSRESOURCEERR);
> 			return;
> 	leak here ------^
> ...
> 
> This leak is easily fixed by just kfree()'ing the memory allocated to 
> 'b3cmsg' right before we return. The following patch does that.
> 
> 
> Signed-off-by: Jesper Juhl <jj@...osbits.net>

Acked-by: Tilman Schmidt <tilman@...p.cc>

> ---
>  capi.c |    1 +
>  1 file changed, 1 insertion(+)
> 
>   compile tested only since I have no way to actually test this.
> 
> diff --git a/drivers/isdn/gigaset/capi.c b/drivers/isdn/gigaset/capi.c
> index bcc174e..658e75f 100644
> --- a/drivers/isdn/gigaset/capi.c
> +++ b/drivers/isdn/gigaset/capi.c
> @@ -1900,6 +1900,7 @@ static void do_disconnect_req(struct gigaset_capi_ctr *iif,
>  		if (b3skb == NULL) {
>  			dev_err(cs->dev, "%s: out of memory\n", __func__);
>  			send_conf(iif, ap, skb, CAPI_MSGOSRESOURCEERR);
> +			kfree(b3cmsg);
>  			return;
>  		}
>  		capi_cmsg2message(b3cmsg,
> 
> 

-- 
Tilman Schmidt                    E-Mail: tilman@...p.cc
Bonn, Germany
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