From: Will Deacon <will@xxxxxxxxxx> commit 4ac2813cc867ae563a1ba5a9414bfb554e5796fa upstream. Ensure the SSID element is bounds-checked prior to invoking memcpy() with its length field, when copying to userspace. Cc: <stable@xxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Reported-by: Nicolas Waisman <nico@xxxxxxxxxx> Signed-off-by: Will Deacon <will@xxxxxxxxxx> Link: https://lore.kernel.org/r/20191004095132.15777-2-will@xxxxxxxxxx [adjust commit log a bit] Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/wireless/wext-sme.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/wireless/wext-sme.c +++ b/net/wireless/wext-sme.c @@ -202,6 +202,7 @@ int cfg80211_mgd_wext_giwessid(struct ne struct iw_point *data, char *ssid) { struct wireless_dev *wdev = dev->ieee80211_ptr; + int ret = 0; /* call only for station! */ if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION)) @@ -219,7 +220,10 @@ int cfg80211_mgd_wext_giwessid(struct ne 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 ne } wdev_unlock(wdev); - return 0; + return ret; } int cfg80211_mgd_wext_siwap(struct net_device *dev,
