CVE-2024-53057 Information

Nov 20, 2024 cve

Description

In the Linux kernel the following vulnerability has been resolved:

net/sched: stop qdisc_tree_reduce_backlog on TC_H_ROOT

In qdisc_tree_reduce_backlog Qdiscs with major handle ffff: are assumed to be either root or ingress. This assumption is bogus since it’s valid to create egress qdiscs with major handle ffff: Budimir Markovic found that for qdiscs like DRR that maintain an active class list it will cause a UAF with a dangling class pointer.

In 066a3b5b2346 the concern was to avoid iterating over the ingress qdisc since its parent is itself. The proper fix is to stop when parent TC_H_ROOT is reached because the only way to retrieve ingress is when a hierarchy which does not contain a ffff: major handle call into qdisc_lookup with TC_H_MAJ(TC_H_ROOT).

In the scenario where major ffff: is an egress qdisc in any of the tree levels the updates will also propagate to TC_H_ROOT which then the iteration must stop.

net/sched/sch_api.c | 2 +- 1 file changed 1 insertion(+) 1 deletion(-)

Reference

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