On Wed, Oct 09, 2019 at 08:41:09AM +0200, Johannes Berg wrote:
From: Johannes Berg johannes.berg@intel.com
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 6168db3c35e4..4a10ab388e0b 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 */- }
for_each_element() is not in 4.4, 4.9, 4.14, or 4.19, so this breaks the build :(
I'll drop this from my queues for now.
thanks,
greg k-h