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    SubjectRe: [GIT PULL] New TPM driver, hwrng driver and fixes
    On 07/27/2012 01:30 PM, Kent Yoder wrote:

    > +
    > + do {
    > + tpm_cmd.header.in = tpm_getrandom_header;
    > + tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
    > +
    > + err = transmit_cmd(chip, &tpm_cmd,
    > + TPM_GETRANDOM_RESULT_SIZE + num_bytes,
    > + "attempting get random");
    > + if (err) {
    > + /* err can be positive if it came from the TPM itself,
    > + * so return a negative value here instead. */
    > + err = -EFAULT;

    -EFAULT is definitely wrong (that means a bad pointer was passed), you
    can use -EIO instead.

    However, I would suggest:

    err = total ? total : -EIO;

    ... so you report the number of bytes successfully received if we got
    any. However, since you *also* do that on the retry line,

    > + goto out_err;
    > + }
    > +
    > + recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
    > + memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
    > +
    > + dest += recd;
    > + total += recd;
    > + num_bytes -= recd;
    > + } while (retries-- && total < max);
    > +
    > + err = total;

    Should we return something other than 0 if we run out of retries here, too?

    Perhaps we should just do the same "err = total ? total : -EIO;" here
    and the above statement can just turn into a break;.

    > - ret = my_get_random(hash, SHA1_DIGEST_SIZE);
    > + ret = tpm_get_random(TPM_ANY_NUM, hash, SHA1_DIGEST_SIZE);
    > if (ret < 0)
    > return ret;

    You are still not checking the return values correctly!

    This needs to be something like:

    ret = tpm_get_random(TPM_ANY_NUM, hash, SHA1_DIGEST_SIZE);
    if (ret != SHA1_DIGEST_SIZE)
    return -EIO; /* Or whatever is appropriate here */


    -hpa


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