From: Pedro Tammela pctammela@mojatatu.com

mainline inclusion from mainline-v6.5-rc2 commit 3e337087c3b5805fe0b8a46ba622a962880b5d64 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7N3MX CVE: CVE-2023-3611

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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 nnamrec@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: Pedro Tammela pctammela@mojatatu.com Reviewed-by: Simon Horman simon.horman@corigine.com Signed-off-by: Paolo Abeni pabeni@redhat.com

Conflicts: net/sched/sch_qfq.c

Signed-off-by: Zhengchao Shao shaozhengchao@huawei.com --- net/sched/sch_qfq.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 0326793b700b..a08579a5f75e 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -116,6 +116,7 @@

#define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */ #define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */ +#define QFQ_MAX_LMAX (1UL << QFQ_MTU_SHIFT)

#define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */

@@ -387,8 +388,13 @@ 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)