diff options
| author | Fernando Fernandez Mancera <fmancera@suse.de> | 2026-04-08 12:00:44 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-12 11:38:18 -0700 |
| commit | a6bd339dbb3514bce690fdcf252e788dfab4ee76 (patch) | |
| tree | 7e64d0d3de4a4a4f197455f6603c258cefa25452 /include | |
| parent | 656121b155030086b01cfce9bd31b0c925ee6860 (diff) | |
| download | lwn-a6bd339dbb3514bce690fdcf252e788dfab4ee76.tar.gz lwn-a6bd339dbb3514bce690fdcf252e788dfab4ee76.zip | |
net_sched: fix skb memory leak in deferred qdisc drops
When the network stack cleans up the deferred list via qdisc_run_end(),
it operates on the root qdisc. If the root qdisc do not implement the
TCQ_F_DEQUEUE_DROPS flag the packets queue to free are never freed and
gets stranded on the child's local to_free list.
Fix this by making qdisc_dequeue_drop() aware of the root qdisc. It
fetches the root qdisc and check for the TCQ_F_DEQUEUE_DROPS flag. If
the flag is present, the packet is appended directly to the root's
to_free list. Otherwise, drop it directly as it was done before the
optimization was implemented.
Fixes: a6efc273ab82 ("net_sched: use qdisc_dequeue_drop() in cake, codel, fq_codel")
Reported-by: Damilola Bello <damilola@aterlo.com>
Closes: https://lore.kernel.org/netdev/CAPgFtOLaedBMU0f_BxV2bXftTJSmJr018Q5uozOo5vVo6b9tjw@mail.gmail.com/
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260408100044.4530-1-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/sch_generic.h | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index c3d657359a3d..5fc0b1ebaf25 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -1170,12 +1170,22 @@ static inline void tcf_kfree_skb_list(struct sk_buff *skb) static inline void qdisc_dequeue_drop(struct Qdisc *q, struct sk_buff *skb, enum skb_drop_reason reason) { + struct Qdisc *root; + DEBUG_NET_WARN_ON_ONCE(!(q->flags & TCQ_F_DEQUEUE_DROPS)); DEBUG_NET_WARN_ON_ONCE(q->flags & TCQ_F_NOLOCK); - tcf_set_drop_reason(skb, reason); - skb->next = q->to_free; - q->to_free = skb; + rcu_read_lock(); + root = qdisc_root_sleeping(q); + + if (root->flags & TCQ_F_DEQUEUE_DROPS) { + tcf_set_drop_reason(skb, reason); + skb->next = root->to_free; + root->to_free = skb; + } else { + kfree_skb_reason(skb, reason); + } + rcu_read_unlock(); } /* Instead of calling kfree_skb() while root qdisc lock is held, |