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(-)
CVSS
7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
from 066a3b5b2346febf9a655b444567b7138e3bb939 before e7f9a6f97eb067599a74f3bcb6761976b0ed303e; from 066a3b5b2346febf9a655b444567b7138e3bb939 before dbe778b08b5101df9e89bc06e0a3a7ecd2f4ef20; from 066a3b5b2346febf9a655b444567b7138e3bb939 before ce691c814bc7a3c30c220ffb5b7422715458fd9b; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 05df1b1dff8f197f1c275b57ccb2ca33021df552; from 066a3b5b2346febf9a655b444567b7138e3bb939 before 580b3189c1972aff0f993837567d36392e9d981b; from 066a3b5b2346febf9a655b444567b7138e3bb939 before 597cf9748c3477bf61bc35f0634129f56764ad24; from 066a3b5b2346febf9a655b444567b7138e3bb939 before 9995909615c3431a5304c1210face5f268d24dba; 066a3b5b2346febf9a655b444567b7138e3bb939 builds before 2e95c4384438adeaa772caa560244b1a2efef816
from 2.6.25 before 4.19.323; from 4.20 before 5.4.285; from 5.5 before 5.10.229; from 5.11 before 5.15.171; from 5.16 before 6.1.116; from 6.2 before 6.6.60; from 6.7 before 6.11.7; 6.12; and 4 more ranges
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.
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