cfg80211: wext: avoid copying malformed SSIDs
Ensure the SSID element is bounds-checked prior to invoking memcpy() with its length field, when copying to userspace. Cc: <stable@vger.kernel.org> Cc: Kees Cook <keescook@chromium.org> Reported-by: Nicolas Waisman <nico@semmle.com> Signed-off-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20191004095132.15777-2-will@kernel.org [adjust commit log a bit] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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@ -202,6 +202,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
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struct iw_point *data, char *ssid)
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{
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struct wireless_dev *wdev = dev->ieee80211_ptr;
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int ret = 0;
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/* call only for station! */
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if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
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@ -219,6 +220,9 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
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if (ie) {
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data->flags = 1;
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data->length = ie[1];
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if (data->length > IW_ESSID_MAX_SIZE)
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ret = -EINVAL;
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else
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memcpy(ssid, ie + 2, data->length);
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}
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rcu_read_unlock();
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@ -229,7 +233,7 @@ int cfg80211_mgd_wext_giwessid(struct net_device *dev,
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}
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wdev_unlock(wdev);
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return 0;
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return ret;
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}
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int cfg80211_mgd_wext_siwap(struct net_device *dev,
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