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

commit 158810b261d02fc7dd92ca9c392d8f8a211a2401 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index d5610e145da208d75b5bc0a4c44e1610ae3b83a7..e150d08f182d81d4b8ebfbad751a7b892589dac7 100644 (file)
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -428,10 +428,17 @@ 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;