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[FIPS 8.7 Legacy] net_sched: hfsc: Address reentrant enqueue adding class to eltree twice #510

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[FIPS 8.7 Legacy] net_sched: hfsc: Address reentrant enqueue adding class to eltree twice #510

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42a4cad
net_sched: hfsc: Fix a UAF vulnerability in class with netem as child…
pvts-mat Aug 11, 2025
80897f5
net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
pvts-mat Aug 12, 2025
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9 changes: 8 additions & 1 deletion net/sched/sch_hfsc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,11 @@ struct hfsc_sched {

#define HT_INFINITY 0xffffffffffffffffULL /* infinite time value */

static bool cl_in_el_or_vttree(struct hfsc_class *cl)
{
return ((cl->cl_flags & HFSC_FSC) && cl->cl_nactive) ||
((cl->cl_flags & HFSC_RSC) && !RB_EMPTY_NODE(&cl->el_node));
}

/*
* eligible tree holds backlogged classes being sorted by their eligible times.
Expand Down Expand Up @@ -1033,6 +1038,8 @@ hfsc_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
if (cl == NULL)
return -ENOBUFS;

RB_CLEAR_NODE(&cl->el_node);

err = tcf_block_get(&cl->block, &cl->filter_list, sch, extack);
if (err) {
kfree(cl);
Expand Down Expand Up @@ -1568,7 +1575,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
return err;
}

if (first) {
if (first && !cl_in_el_or_vttree(cl)) {
if (cl->cl_flags & HFSC_RSC)
init_ed(cl, len);
if (cl->cl_flags & HFSC_FSC)
Expand Down