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    Subject[PATCH 4.11 10/78] mac80211/wpa: use constant time memory comparison for MACs
    Date
    4.11-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jason A. Donenfeld <Jason@zx2c4.com>

    commit 98c67d187db7808b1f3c95f2110dd4392d034182 upstream.

    Otherwise, we enable all sorts of forgeries via timing attack.

    Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
    Cc: Johannes Berg <johannes@sipsolutions.net>
    Cc: linux-wireless@vger.kernel.org
    Signed-off-by: Johannes Berg <johannes.berg@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/mac80211/wpa.c | 9 +++++----
    1 file changed, 5 insertions(+), 4 deletions(-)

    --- a/net/mac80211/wpa.c
    +++ b/net/mac80211/wpa.c
    @@ -17,6 +17,7 @@
    #include <asm/unaligned.h>
    #include <net/mac80211.h>
    #include <crypto/aes.h>
    +#include <crypto/algapi.h>

    #include "ieee80211_i.h"
    #include "michael.h"
    @@ -153,7 +154,7 @@ ieee80211_rx_h_michael_mic_verify(struct
    data_len = skb->len - hdrlen - MICHAEL_MIC_LEN;
    key = &rx->key->conf.key[NL80211_TKIP_DATA_OFFSET_RX_MIC_KEY];
    michael_mic(key, hdr, data, data_len, mic);
    - if (memcmp(mic, data + data_len, MICHAEL_MIC_LEN) != 0)
    + if (crypto_memneq(mic, data + data_len, MICHAEL_MIC_LEN))
    goto mic_fail;

    /* remove Michael MIC from payload */
    @@ -1048,7 +1049,7 @@ ieee80211_crypto_aes_cmac_decrypt(struct
    bip_aad(skb, aad);
    ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
    skb->data + 24, skb->len - 24, mic);
    - if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
    + if (crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
    key->u.aes_cmac.icverrors++;
    return RX_DROP_UNUSABLE;
    }
    @@ -1098,7 +1099,7 @@ ieee80211_crypto_aes_cmac_256_decrypt(st
    bip_aad(skb, aad);
    ieee80211_aes_cmac_256(key->u.aes_cmac.tfm, aad,
    skb->data + 24, skb->len - 24, mic);
    - if (memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
    + if (crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
    key->u.aes_cmac.icverrors++;
    return RX_DROP_UNUSABLE;
    }
    @@ -1202,7 +1203,7 @@ ieee80211_crypto_aes_gmac_decrypt(struct
    if (ieee80211_aes_gmac(key->u.aes_gmac.tfm, aad, nonce,
    skb->data + 24, skb->len - 24,
    mic) < 0 ||
    - memcmp(mic, mmie->mic, sizeof(mmie->mic)) != 0) {
    + crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
    key->u.aes_gmac.icverrors++;
    return RX_DROP_UNUSABLE;
    }

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