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    Subject[PATCH 4.14 095/119] mac80211: Reject malformed SSID elements
    Date
    From: Will Deacon <will@kernel.org>

    commit 4152561f5da3fca92af7179dd538ea89e248f9d0 upstream.

    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: 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/20191004095132.15777-1-will@kernel.org
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

    --- a/net/mac80211/mlme.c
    +++ b/net/mac80211/mlme.c
    @@ -2430,7 +2430,8 @@ struct sk_buff *ieee80211_ap_probereq_ge

    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];
    @@ -4756,7 +4757,7 @@ int ieee80211_mgd_assoc(struct ieee80211

    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;

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