cf8ecd6ea6
commit 3e337087c3b5805fe0b8a46ba622a962880b5d64 upstream.
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>
Signed-off-by: Shaoying Xu <shaoyi@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.