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authorJohannes Berg <johannes.berg@intel.com>2019-09-20 21:54:17 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-10-11 18:21:44 +0200
commit1bd17a737c9e7e91483d9a603528b0e6d4c772f8 (patch)
tree91a664eb08f6e1b7c4b58d802d95958b2e7af4b5
parent527ba5d7634b230448c133b6eea304146ec0aa5e (diff)
nl80211: validate beacon head
commit f88eb7c0d002a67ef31aeb7850b42ff69abc46dc upstream. We currently don't validate the beacon head, i.e. the header, fixed part and elements that are to go in front of the TIM element. This means that the variable elements there can be malformed, e.g. have a length exceeding the buffer size, but most downstream code from this assumes that this has already been checked. Add the necessary checks to the netlink policy. Cc: stable@vger.kernel.org Fixes: ed1b6cc7f80f ("cfg80211/nl80211: add beacon settings") Link: https://lore.kernel.org/r/1569009255-I7ac7fbe9436e9d8733439eab8acbbd35e55c74ef@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/wireless/nl80211.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a2a64c915a9d..334e3181f1c5 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -200,6 +200,38 @@ cfg80211_get_dev_from_info(struct net *netns, struct genl_info *info)
return __cfg80211_rdev_from_attrs(netns, info->attrs);
}
+static int validate_beacon_head(const struct nlattr *attr,
+ struct netlink_ext_ack *extack)
+{
+ const u8 *data = nla_data(attr);
+ unsigned int len = nla_len(attr);
+ const struct element *elem;
+ const struct ieee80211_mgmt *mgmt = (void *)data;
+ unsigned int fixedlen = offsetof(struct ieee80211_mgmt,
+ u.beacon.variable);
+
+ if (len < fixedlen)
+ goto err;
+
+ if (ieee80211_hdrlen(mgmt->frame_control) !=
+ offsetof(struct ieee80211_mgmt, u.beacon))
+ goto err;
+
+ data += fixedlen;
+ len -= fixedlen;
+
+ for_each_element(elem, data, len) {
+ /* nothing */
+ }
+
+ if (for_each_element_completed(elem, data, len))
+ return 0;
+
+err:
+ NL_SET_ERR_MSG_ATTR(extack, attr, "malformed beacon head");
+ return -EINVAL;
+}
+
/* policy for the attributes */
static const struct nla_policy nl80211_policy[NUM_NL80211_ATTR] = {
[NL80211_ATTR_WIPHY] = { .type = NLA_U32 },
@@ -4016,6 +4048,12 @@ static int nl80211_parse_beacon(struct nlattr *attrs[],
memset(bcn, 0, sizeof(*bcn));
if (attrs[NL80211_ATTR_BEACON_HEAD]) {
+ int ret = validate_beacon_head(attrs[NL80211_ATTR_BEACON_HEAD],
+ NULL);
+
+ if (ret)
+ return ret;
+
bcn->head = nla_data(attrs[NL80211_ATTR_BEACON_HEAD]);
bcn->head_len = nla_len(attrs[NL80211_ATTR_BEACON_HEAD]);
if (!bcn->head_len)