From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>,
syzbot+07f3f38f723c335f106d@syzkaller.appspotmail.com
Subject: [PATCH net] net/sched: sch_qfq: do not free existing class in qfq_change_class()
Date: Mon, 12 Jan 2026 17:56:56 +0000 [thread overview]
Message-ID: <20260112175656.17605-1-edumazet@google.com> (raw)
Fixes qfq_change_class() error case.
cl->qdisc and cl should only be freed if a new class and qdisc
were allocated, or we risk various UAF.
Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost")
Reported-by: syzbot+07f3f38f723c335f106d@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6965351d.050a0220.eaf7.00c5.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/sched/sch_qfq.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index f4013b547438ffe1bdc8ba519971a1681df4700b..9d59090bbe934ad56ab08a59708aab375aa77cf0 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -529,8 +529,10 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
return 0;
destroy_class:
- qdisc_put(cl->qdisc);
- kfree(cl);
+ if (!existing) {
+ qdisc_put(cl->qdisc);
+ kfree(cl);
+ }
return err;
}
--
2.52.0.457.g6b5491de43-goog
next reply other threads:[~2026-01-12 17:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-12 17:56 Eric Dumazet [this message]
2026-01-12 18:26 ` [PATCH net] net/sched: sch_qfq: do not free existing class in qfq_change_class() Jamal Hadi Salim
2026-01-12 18:38 ` Eric Dumazet
2026-01-14 3:40 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260112175656.17605-1-edumazet@google.com \
--to=edumazet@google.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=horms@kernel.org \
--cc=jhs@mojatatu.com \
--cc=jiri@resnulli.us \
--cc=kuba@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=syzbot+07f3f38f723c335f106d@syzkaller.appspotmail.com \
--cc=xiyou.wangcong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox