ACK: [SRU OEM-5.14, OEM-5.17 1/1] net: sched: Fix use after free in red_enqueue()

[Andrei Gherzan]

On 23/04/21 04:34AM, Cengiz Can wrote:
> From: Dan Carpenter <dan.carpenter at oracle.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2017013
> 
> We can't use "skb" again after passing it to qdisc_enqueue().  This is
> basically identical to commit 2f09707d0c97 ("sch_sfb: Also store skb
> len before calling child enqueue").
> 
> Fixes: d7f4f332f082 ("sch_red: update backlog as well")
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> Reviewed-by: Eric Dumazet <edumazet at google.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 8bdc2acd420c6f3dd1f1c78750ec989f02a1e2b9)
> Signed-off-by: Cengiz Can <cengiz.can at canonical.com>

Acked-by: Andrei Gherzan <andrei.gherzan at canonical.com>

> ---
>  net/sched/sch_red.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
> index 40adf1f07a82..b310842b4225 100644
> --- a/net/sched/sch_red.c
> +++ b/net/sched/sch_red.c
> @@ -72,6 +72,7 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
>  {
>  	struct red_sched_data *q = qdisc_priv(sch);
>  	struct Qdisc *child = q->qdisc;
> +	unsigned int len;
>  	int ret;
>  
>  	q->vars.qavg = red_calc_qavg(&q->parms,
> @@ -126,9 +127,10 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
>  		break;
>  	}
>  
> +	len = qdisc_pkt_len(skb);
>  	ret = qdisc_enqueue(skb, child, to_free);
>  	if (likely(ret == NET_XMIT_SUCCESS)) {
> -		qdisc_qstats_backlog_inc(sch, skb);
> +		sch->qstats.backlog += len;
>  		sch->q.qlen++;
>  	} else if (net_xmit_drop_count(ret)) {
>  		q->stats.pdrop++;
> -- 
> 2.37.2
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

-- 
Andrei Gherzan
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20230421/a2297c20/attachment.sig>