First published: Tue Nov 19 2024(Updated: )
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(-)
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Software | Affected Version | How to fix |
---|---|---|
Linux Linux kernel | >=2.6.25<4.19.323 | |
Linux Linux kernel | >=4.20<5.4.285 | |
Linux Linux kernel | >=5.5<5.10.229 | |
Linux Linux kernel | >=5.11<5.15.171 | |
Linux Linux kernel | >=5.16<6.1.116 | |
Linux Linux kernel | >=6.2<6.6.60 | |
Linux Linux kernel | >=6.7<6.11.7 | |
Linux Linux kernel | =6.12-rc1 | |
Linux Linux kernel | =6.12-rc2 | |
Linux Linux kernel | =6.12-rc3 | |
Linux Linux kernel | =6.12-rc4 | |
Linux Linux kernel | =6.12-rc5 |
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