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    Subject[PATCH 4.9 63/72] crypto: dh - Dont permit key or g size longer than p
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    From: Eric Biggers <ebiggers@google.com>

    commit ccd9888f14a8019c0bbdeeae758aba1f58693712 upstream.

    The "qat-dh" DH implementation assumes that 'key' and 'g' can be copied
    into a buffer with size 'p_size'. However it was never checked that
    that was actually the case, which most likely allowed users to cause a
    buffer underflow via KEYCTL_DH_COMPUTE.

    Fix this by updating crypto_dh_decode_key() to verify this precondition
    for all DH implementations.

    Fixes: c9839143ebbf ("crypto: qat - Add DH support")
    Signed-off-by: Eric Biggers <ebiggers@google.com>
    Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    crypto/dh_helper.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    --- a/crypto/dh_helper.c
    +++ b/crypto/dh_helper.c
    @@ -83,6 +83,14 @@ int crypto_dh_decode_key(const char *buf
    if (secret.len != crypto_dh_key_len(params))
    return -EINVAL;

    + /*
    + * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since
    + * some drivers assume otherwise.
    + */
    + if (params->key_size > params->p_size ||
    + params->g_size > params->p_size)
    + return -EINVAL;
    +
    /* Don't allocate memory. Set pointers to data within
    * the given buffer
    */

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