From: Pedro Tammela <pctammela@mojatatu.com> stable inclusion from stable-v4.19.323 commit e7f9a6f97eb067599a74f3bcb6761976b0ed303e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IB5KR7 CVE: CVE-2024-53057 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 2e95c4384438adeaa772caa560244b1a2efef816 ] 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. Fixes: 066a3b5b2346 ("[NET_SCHED] sch_api: fix qdisc_tree_decrease_qlen() loop") Reported-by: Budimir Markovic <markovicbudimir@gmail.com> Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com> Tested-by: Victor Nogueira <victor@mojatatu.com> Signed-off-by: Pedro Tammela <pctammela@mojatatu.com> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> net/sched/sch_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20241024165547.418570-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> Reviewed-by: Zhang Changzhong <zhangchangzhong@huaiwei.com> --- net/sched/sch_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index 458f9e733cf0..36a5d3ceead2 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -783,7 +783,7 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n, drops = max_t(int, n, 0); rcu_read_lock(); while ((parentid = sch->parent)) { - if (TC_H_MAJ(parentid) == TC_H_MAJ(TC_H_INGRESS)) + if (parentid == TC_H_ROOT) break; if (sch->flags & TCQ_F_NOPARENT) -- 2.25.1