Ensure the SSID element is bounds-checked prior to invoking memcpy() with its length field.

Cc: stable@vger.kernel.org Cc: Johannes Berg johannes@sipsolutions.net Cc: Kees Cook keescook@chromium.org Reported-by: Nicolas Waisman nico@semmle.com Signed-off-by: Will Deacon will@kernel.org --- net/wireless/wext-sme.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c index c67d7a82ab13..3fd2cc7fc36a 100644 --- a/net/wireless/wext-sme.c +++ b/net/wireless/wext-sme.c @@ -201,6 +201,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev, struct iw_request_info *info, struct iw_point *data, char *ssid) { + int ret = 0; struct wireless_dev *wdev = dev->ieee80211_ptr;

/* call only for station! */ @@ -219,7 +220,10 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev, if (ie) { data->flags = 1; data->length = ie[1]; - memcpy(ssid, ie + 2, data->length); + if (data->length > IW_ESSID_MAX_SIZE) + ret = -EINVAL; + else + memcpy(ssid, ie + 2, data->length); } rcu_read_unlock(); } else if (wdev->wext.connect.ssid && wdev->wext.connect.ssid_len) { @@ -229,7 +233,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev, } wdev_unlock(wdev);

- return 0; + return ret; }

int cfg80211_mgd_wext_siwap(struct net_device *dev,

On Fri, Oct 04, 2019 at 10:51:31AM +0100, Will Deacon wrote:

Although this shouldn't occur in practice, it's a good idea to bounds check the length field of the SSID element prior to using it for things like allocations or memcpy operations.

Cc: stable@vger.kernel.org Cc: Johannes Berg johannes@sipsolutions.net Cc: Kees Cook keescook@chromium.org Reported-by: Nicolas Waisman nico@semmle.com Signed-off-by: Will Deacon will@kernel.org

Reviewed-by: Kees Cook keescook@chromium.org

-Kees

---

net/mac80211/mlme.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c index 26a2f49208b6..54dd8849d1cc 100644 --- a/net/mac80211/mlme.c +++ b/net/mac80211/mlme.c @@ -2633,7 +2633,8 @@ struct sk_buff *ieee80211_ap_probereq_get(struct ieee80211_hw *hw, rcu_read_lock(); ssid = ieee80211_bss_get_ie(cbss, WLAN_EID_SSID);

• if (WARN_ON_ONCE(ssid == NULL))

• if (WARN_ONCE(!ssid || ssid[1] > IEEE80211_MAX_SSID_LEN,

•       "invalid SSID element (len=%d)", ssid ? ssid[1] : -1))
  

  ssid_len = 0; else ssid_len = ssid[1];

@@ -5233,7 +5234,7 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata, rcu_read_lock(); ssidie = ieee80211_bss_get_ie(req->bss, WLAN_EID_SSID);

• if (!ssidie) {

• if (!ssidie || ssidie[1] > sizeof(assoc_data->ssid)) { rcu_read_unlock(); kfree(assoc_data); return -EINVAL;

-- 2.23.0.581.g78d2f28ef7-goog