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authorPedro Tammela <pctammela@mojatatu.com>2024-10-24 18:55:47 +0200
committerJakub Kicinski <kuba@kernel.org>2024-10-29 19:32:26 +0100
commit2e95c4384438adeaa772caa560244b1a2efef816 (patch)
treef6a197ed9e1774a29bd1d35ba11283c9b1aa47c2 /net/sched/sch_api.c
parentselftests: netfilter: nft_flowtable.sh: make first pass deterministic (diff)
downloadlinux-2e95c4384438adeaa772caa560244b1a2efef816.tar.xz
linux-2e95c4384438adeaa772caa560244b1a2efef816.zip
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. 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>
Diffstat (limited to 'net/sched/sch_api.c')
-rw-r--r--net/sched/sch_api.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 2eefa4783879..a1d27bc039a3 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -791,7 +791,7 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, int n, int len)
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)