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| author | Victor Nogueira <victor@mojatatu.com> | 2025-04-25 19:07:06 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-09 09:41:40 +0200 |
| commit | 8df7d37d626430035b413b97cee18396b3450bef (patch) | |
| tree | 28ddeaffb8b96b6fcc06543e8963bc14c2c00d3e /net/sched | |
| parent | 4f0ecf50cdf76da95828578a92f130b653ac2fcf (diff) | |
| download | linux-8df7d37d626430035b413b97cee18396b3450bef.tar.gz linux-8df7d37d626430035b413b97cee18396b3450bef.tar.bz2 linux-8df7d37d626430035b413b97cee18396b3450bef.zip | |
net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc
[ Upstream commit 141d34391abbb315d68556b7c67ad97885407547 ]
As described in Gerrard's report [1], we have a UAF case when an hfsc class
has a netem child qdisc. The crux of the issue is that hfsc is assuming
that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted
the class in the vttree or eltree (which is not true for the netem
duplicate case).
This patch checks the n_active class variable to make sure that the code
won't insert the class in the vttree or eltree twice, catering for the
reentrant case.
[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
Fixes: 37d9cf1a3ce3 ("sched: Fix detection of empty queues in child qdiscs")
Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20250425220710.3964791-3-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/sch_hfsc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index dbed490aafd3..4b9f323845b9 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -1564,7 +1564,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) return err; } - if (first) { + if (first && !cl->cl_nactive) { if (cl->cl_flags & HFSC_RSC) init_ed(cl, len); if (cl->cl_flags & HFSC_FSC) |