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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: d03b195b5a ("sch_htb: Hierarchical QoS hardware offload")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
rM2-mainline
Maxim Mikityanskiy 2021-03-11 16:42:05 +02:00 committed by David S. Miller
parent 7a1468ba0e
commit 93bde210c4
1 changed files with 4 additions and 0 deletions
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4
net/sched/sch_htb.c
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@ -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),