From 93bde210c4341e79f0cd9cb160d889f4577e40b1 Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Thu, 11 Mar 2021 16:42:05 +0200 Subject: [PATCH] sch_htb: Fix select_queue for non-offload mode htb_select_queue assumes it's always the offload mode, and it ends up in calling ndo_setup_tc without any checks. It may lead to a NULL pointer dereference if ndo_setup_tc is not implemented, or to an error returned from the driver, which will prevent attaching qdiscs to HTB classes in the non-offload mode. This commit fixes the bug by adding the missing check to htb_select_queue. In the non-offload mode it will return sch->dev_queue, mimicking tc_modify_qdisc's behavior for the case where select_queue is not implemented. Reported-by: syzbot+b53a709f04722ca12a3c@syzkaller.appspotmail.com Fixes: d03b195b5aa0 ("sch_htb: Hierarchical QoS hardware offload") Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan Signed-off-by: David S. Miller --- net/sched/sch_htb.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index dff3adf5a915..b23203159996 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -1340,8 +1340,12 @@ htb_select_queue(struct Qdisc *sch, struct tcmsg *tcm) { struct net_device *dev = qdisc_dev(sch); struct tc_htb_qopt_offload offload_opt; + struct htb_sched *q = qdisc_priv(sch); int err; + if (!q->offload) + return sch->dev_queue; + offload_opt = (struct tc_htb_qopt_offload) { .command = TC_HTB_LEAF_QUERY_QUEUE, .classid = TC_H_MIN(tcm->tcm_parent),