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| author | Pedro Tammela <pctammela@mojatatu.com> | 2024-10-24 18:55:47 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-10-29 19:32:26 +0100 |
| commit | 2e95c4384438adeaa772caa560244b1a2efef816 (patch) | |
| tree | f6a197ed9e1774a29bd1d35ba11283c9b1aa47c2 /net | |
| parent | selftests: netfilter: nft_flowtable.sh: make first pass deterministic (diff) | |
| download | linux-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')
| -rw-r--r-- | net/sched/sch_api.c | 2 |
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) |