netdev - Re: [PATCH] netem: fix possible skb leak

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 30 Apr 2012 09:25:09 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Stephen Hemminger <shemminger@...l.org>
Subject: Re: [PATCH] netem: fix possible skb leak

On Sun, 29 Apr 2012 21:08:22 +0200
Eric Dumazet <eric.dumazet@...il.com> wrote:

> From: Eric Dumazet <edumazet@...gle.com>
> 
> skb_checksum_help(skb) can return an error, we must free skb in this
> case. qdisc_drop(skb, sch) can also be feeded with a NULL skb (if
> skb_unshare() failed), so lets use this generic helper.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Stephen Hemminger <shemminger@...l.org>
> ---
>  net/sched/sch_netem.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> index 5da548f..ebd2296 100644
> --- a/net/sched/sch_netem.c
> +++ b/net/sched/sch_netem.c
> @@ -408,10 +408,8 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  	if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
>  		if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
>  		    (skb->ip_summed == CHECKSUM_PARTIAL &&
> -		     skb_checksum_help(skb))) {
> -			sch->qstats.drops++;
> -			return NET_XMIT_DROP;
> -		}
> +		     skb_checksum_help(skb)))
> +			return qdisc_drop(skb, sch);
>  
>  		skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
>  	}
> 
> 

This would crater if skb_unshare() returned NULL. I think the conditional
needs to be split into two paths.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html