diff options
| author | Yunjian Wang <wangyunjian@huawei.com> | 2021-06-04 19:03:18 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-06-04 14:44:18 -0700 |
| commit | 944d671d5faa0d78980a3da5c0f04960ef1ad893 (patch) | |
| tree | 61215bceb853496d1e709ad7a4ad2658878d51f6 | |
| parent | 26821ecd3b489c11ecfbd3942bc7fef7629464b6 (diff) | |
sch_htb: fix refcount leak in htb_parent_to_leaf_offload
The commit ae81feb7338c ("sch_htb: fix null pointer dereference
on a null new_q") fixes a NULL pointer dereference bug, but it
is not correct.
Because htb_graft_helper properly handles the case when new_q
is NULL, and after the previous patch by skipping this call
which creates an inconsistency : dev_queue->qdisc will still
point to the old qdisc, but cl->parent->leaf.q will point to
the new one (which will be noop_qdisc, because new_q was NULL).
The code is based on an assumption that these two pointers are
the same, so it can lead to refcount leaks.
The correct fix is to add a NULL pointer check to protect
qdisc_refcount_inc inside htb_parent_to_leaf_offload.
Fixes: ae81feb7338c ("sch_htb: fix null pointer dereference on a null new_q")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Suggested-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/sched/sch_htb.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 081c11d5717c..8827987ba903 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -1488,7 +1488,8 @@ static void htb_parent_to_leaf_offload(struct Qdisc *sch, struct Qdisc *old_q; /* One ref for cl->leaf.q, the other for dev_queue->qdisc. */ - qdisc_refcount_inc(new_q); + if (new_q) + qdisc_refcount_inc(new_q); old_q = htb_graft_helper(dev_queue, new_q); WARN_ON(!(old_q->flags & TCQ_F_BUILTIN)); } @@ -1675,10 +1676,9 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg, cl->parent->common.classid, NULL); if (q->offload) { - if (new_q) { + if (new_q) htb_set_lockdep_class_child(new_q); - htb_parent_to_leaf_offload(sch, dev_queue, new_q); - } + htb_parent_to_leaf_offload(sch, dev_queue, new_q); } } |