net/sched: sch_qfq: reintroduce lmax bound check for MTU

25369891fcef deletes a check for the case where no 'lmax' is
specified which 3037933448f6 previously fixed as 'lmax'
could be set to the device's MTU without any bound checking
for QFQ_LMAX_MIN and QFQ_LMAX_MAX. Therefore, reintroduce the check.

Fixes: 25369891fcef ("net/sched: sch_qfq: refactor parsing of netlink parameters")
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index dfd9a99e62570f18d814d3155a7df545d284fc75..63a5b277c117f3100aa17339b39cdfbeb6f1a6b7 100644 (file)
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -423,10 +423,17 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
        else
                weight = 1;
 
-       if (tb[TCA_QFQ_LMAX])
+       if (tb[TCA_QFQ_LMAX]) {
                lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
-       else
+       } else {
+               /* MTU size is user controlled */
                lmax = psched_mtu(qdisc_dev(sch));
+               if (lmax < QFQ_MIN_LMAX || lmax > QFQ_MAX_LMAX) {
+                       NL_SET_ERR_MSG_MOD(extack,
+                                          "MTU size out of bounds for qfq");
+                       return -EINVAL;
+               }
+       }
 
        inv_w = ONE_FP / weight;
        weight = ONE_FP / inv_w;