[PATCH v1] net/sched: mqprio: Add length check for TCA_MQPRIO_{MAX/MIN}_RATE64

[Lin Ma]

The nla_for_each_nested parsing in function mqprio_parse_nlattr() does
not check the length of the nested attribute. This can lead to an
out-of-attribute read and allow a malformed nlattr (e.g., length 0) to
be viewed as 8 byte integer and passed to priv->max_rate/min_rate.

This patch adds the check based on nla_len() when check the nla_type(),
which ensures that the attribute has enough length.

Fixes: 4e8b86c06269 ("mqprio: Introduce new hardware offload mode and shaper in mqprio")
Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
---
 net/sched/sch_mqprio.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index ab69ff7577fc..7bd1d261d8e7 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -285,7 +285,8 @@ static int mqprio_parse_nlattr(struct Qdisc *sch, struct tc_mqprio_qopt *qopt,
 		i = 0;
 		nla_for_each_nested(attr, tb[TCA_MQPRIO_MIN_RATE64],
 				    rem) {
-			if (nla_type(attr) != TCA_MQPRIO_MIN_RATE64) {
+			if (nla_type(attr) != TCA_MQPRIO_MIN_RATE64 ||
+			    nla_len(attr) < sizeof(u64)) {
 				NL_SET_ERR_MSG_ATTR(extack, attr,
 						    "Attribute type expected to be TCA_MQPRIO_MIN_RATE64");
 				return -EINVAL;
@@ -307,7 +308,8 @@ static int mqprio_parse_nlattr(struct Qdisc *sch, struct tc_mqprio_qopt *qopt,
 		i = 0;
 		nla_for_each_nested(attr, tb[TCA_MQPRIO_MAX_RATE64],
 				    rem) {
-			if (nla_type(attr) != TCA_MQPRIO_MAX_RATE64) {
+			if (nla_type(attr) != TCA_MQPRIO_MAX_RATE64 ||
+			    nla_len(attr) < sizeof(u64)) {
 				NL_SET_ERR_MSG_ATTR(extack, attr,
 						    "Attribute type expected to be TCA_MQPRIO_MAX_RATE64");
 				return -EINVAL;
-- 
2.17.1