Hi,

This commit has been processed because it contains a "Fixes:" tag, fixing commit: ed1b6cc7f80f cfg80211/nl80211: add beacon settings.

[...]

NOTE: The patch will not be queued to stable trees until it is upstream.

How should we proceed with this patch?

You tell me! I can make a backport (below), but I don't know what to do with it until the real commit actually makes it upstream ... where did you even find it?

You also need to cherry-pick 0f3b07f027f8 ("cfg80211: add and use strongly typed element iteration macros") 7388afe09143 ("cfg80211: Use const more consistently in for_each_element macros")

as dependencies - the latter doesn't apply cleanly as it has a change that doesn't apply, but that part of the change isn't necessary.

johannes

From 35b3085c0087933b77e36e28776cffac9cf27338 Mon Sep 17 00:00:00 2001

From: Johannes Berg johannes.berg@intel.com Date: Fri, 20 Sep 2019 22:31:24 +0300 Subject: [PATCH] nl80211: validate beacon head

Commit 8a3347aa110c76a7f87771999aed491d1d8779a8 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-I7ac7fbe9436e9d8733439eab8acbbd35e55c74... Signed-off-by: Johannes Berg johannes.berg@intel.com --- net/wireless/nl80211.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 2a85bff6a8f3..58d1b0d5cc84 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 }, @@ -4014,6 +4046,12 @@ 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)