From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D6B371ED38 for ; Tue, 25 Jul 2023 11:28:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA51CC433C8; Tue, 25 Jul 2023 11:28:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690284509; bh=nn4t8r+q/P4qv13ONAIV2jP5y6Hw5AxTxho7KOwNFG0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ad0RohE6y1ERgtWuYX/RdX/1LbCBztqh2w0AcuKeRYTODl4gxPN8xTDhe3tzX9OHO k3ZjYj2UW6+mIsTEAMCWWz/evaolojdP6GZo5wIaWSCRcMXxK1RkKPyxnuCzAfcfWf AL5JSq1c3EPLumxWXh1vbddnjhwpVauO1zf58wiE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lion , Eric Dumazet , Jamal Hadi Salim , Pedro Tammela , Simon Horman , Paolo Abeni , Sasha Levin Subject: [PATCH 5.10 374/509] net/sched: sch_qfq: account for stab overhead in qfq_enqueue Date: Tue, 25 Jul 2023 12:45:13 +0200 Message-ID: <20230725104610.845791451@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104553.588743331@linuxfoundation.org> References: <20230725104553.588743331@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Pedro Tammela [ Upstream commit 3e337087c3b5805fe0b8a46ba622a962880b5d64 ] Lion says: ------- In the QFQ scheduler a similar issue to CVE-2023-31436 persists. Consider the following code in net/sched/sch_qfq.c: static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) { unsigned int len = qdisc_pkt_len(skb), gso_segs; // ... if (unlikely(cl->agg->lmax < len)) { pr_debug("qfq: increasing maxpkt from %u to %u for class %u", cl->agg->lmax, len, cl->common.classid); err = qfq_change_agg(sch, cl, cl->agg->class_weight, len); if (err) { cl->qstats.drops++; return qdisc_drop(skb, sch, to_free); } // ... } Similarly to CVE-2023-31436, "lmax" is increased without any bounds checks according to the packet length "len". Usually this would not impose a problem because packet sizes are naturally limited. This is however not the actual packet length, rather the "qdisc_pkt_len(skb)" which might apply size transformations according to "struct qdisc_size_table" as created by "qdisc_get_stab()" in net/sched/sch_api.c if the TCA_STAB option was set when modifying the qdisc. A user may choose virtually any size using such a table. As a result the same issue as in CVE-2023-31436 can occur, allowing heap out-of-bounds read / writes in the kmalloc-8192 cache. ------- We can create the issue with the following commands: tc qdisc add dev $DEV root handle 1: stab mtu 2048 tsize 512 mpu 0 \ overhead 999999999 linklayer ethernet qfq tc class add dev $DEV parent 1: classid 1:1 htb rate 6mbit burst 15k tc filter add dev $DEV parent 1: matchall classid 1:1 ping -I $DEV 1.1.1.2 This is caused by incorrectly assuming that qdisc_pkt_len() returns a length within the QFQ_MIN_LMAX < len < QFQ_MAX_LMAX. Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Reported-by: Lion Reviewed-by: Eric Dumazet Signed-off-by: Jamal Hadi Salim Signed-off-by: Pedro Tammela Reviewed-by: Simon Horman Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/sched/sch_qfq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 975e444f2d820..616d1798cfef6 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -381,8 +381,13 @@ static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight, u32 lmax) { struct qfq_sched *q = qdisc_priv(sch); - struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight); + struct qfq_aggregate *new_agg; + /* 'lmax' can range from [QFQ_MIN_LMAX, pktlen + stab overhead] */ + if (lmax > QFQ_MAX_LMAX) + return -EINVAL; + + new_agg = qfq_find_agg(q, lmax, weight); if (new_agg == NULL) { /* create new aggregate */ new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC); if (new_agg == NULL) -- 2.39.2