linux-kernel - Re: [PATCH] ISDN: Avoid a potential NULL ptr deref in ippp

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Message-ID: <9a8748490611210537q1f493d11w700099da3243ef39@mail.gmail.com>
Date:	Tue, 21 Nov 2006 14:37:34 +0100
From:	"Jesper Juhl" <jesper.juhl@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	"Michael Hipp" <Michael.Hipp@...dent.uni-tuebingen.de>,
	"Karsten Keil" <kkeil@...e.de>,
	"Kai Germaschewski" <kai.germaschewski@....de>,
	isdn4linux@...tserv.isdn4linux.de,
	"Jesper Juhl" <jesper.juhl@...il.com>, starvik@...s.com,
	dev-etrax@...s.com, "David Rientjes" <rientjes@...washington.edu>
Subject: Re: [PATCH] ISDN: Avoid a potential NULL ptr deref in ippp

Any reason why we can't apply the patch below?

On 30/10/06, Jesper Juhl <jesper.juhl@...il.com> wrote:
>
> There's a potential problem in isdn_ppp.c::isdn_ppp_decompress().
> dev_alloc_skb() may fail and return NULL. If it does we will be passing a
> NULL skb_out to ipc->decompress() and may also end up
> dereferencing a NULL pointer at
>     *proto = isdn_ppp_strip_proto(skb_out);
> Correct this by testing 'skb_out' against NULL early and bail out.
>
>
> Signed-off-by: Jesper Juhl <jesper.juhl@...il.com>
> ---
>
>  drivers/isdn/i4l/isdn_ppp.c |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/isdn/i4l/isdn_ppp.c b/drivers/isdn/i4l/isdn_ppp.c
> index 119412d..5a97ce6 100644
> --- a/drivers/isdn/i4l/isdn_ppp.c
> +++ b/drivers/isdn/i4l/isdn_ppp.c
> @@ -2536,6 +2536,11 @@ static struct sk_buff *isdn_ppp_decompre
>                 rsparm.maxdlen = IPPP_RESET_MAXDATABYTES;
>
>                 skb_out = dev_alloc_skb(is->mru + PPP_HDRLEN);
> +               if (!skb_out) {
> +                       kfree_skb(skb);
> +                       printk(KERN_ERR "ippp: decomp memory allocation failure\n");
> +                       return NULL;
> +               }
>                 len = ipc->decompress(stat, skb, skb_out, &rsparm);
>                 kfree_skb(skb);
>                 if (len <= 0) {
>


-- 
Jesper Juhl <jesper.juhl@...il.com>
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