4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx> [ Upstream commit 38b4f18d56372e1e21771ab7b0357b853330186c ] gred_change_table_def() takes a pointer to TCA_GRED_DPS attribute, and expects it will be able to interpret its contents as struct tc_gred_sopt. Pass the correct gred attribute, instead of TCA_OPTIONS. This bug meant the table definition could never be changed after Qdisc was initialized (unless whatever TCA_OPTIONS contained both passed netlink validation and was a valid struct tc_gred_sopt...). Old behaviour: $ ip link add type dummy $ tc qdisc replace dev dummy0 parent root handle 7: \ gred setup vqs 4 default 0 $ tc qdisc replace dev dummy0 parent root handle 7: \ gred setup vqs 4 default 0 RTNETLINK answers: Invalid argument Now: $ ip link add type dummy $ tc qdisc replace dev dummy0 parent root handle 7: \ gred setup vqs 4 default 0 $ tc qdisc replace dev dummy0 parent root handle 7: \ gred setup vqs 4 default 0 $ tc qdisc replace dev dummy0 parent root handle 7: \ gred setup vqs 4 default 0 Fixes: f62d6b936df5 ("[PKT_SCHED]: GRED: Use central VQ change procedure") Signed-off-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sched/sch_gred.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/sched/sch_gred.c +++ b/net/sched/sch_gred.c @@ -413,7 +413,7 @@ static int gred_change(struct Qdisc *sch if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) { if (tb[TCA_GRED_LIMIT] != NULL) sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]); - return gred_change_table_def(sch, opt); + return gred_change_table_def(sch, tb[TCA_GRED_DPS]); } if (tb[TCA_GRED_PARMS] == NULL ||