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SubjectRe: [PATCH v6] tpm: Check size of response before accessing data
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On 01/17/2017 09:49 AM, Jarkko Sakkinen wrote:
> On Mon, Jan 16, 2017 at 04:41:11PM -0500, Stefan Berger wrote:
>
>> + * @min_rx_length: minimum expected length of response
> Please, rename as min_rsp_body_len and change the description
> accordingly.
>
>> * @flags: tpm transmit flags - bitmap
>> * @desc: command description used in the error message
>> *
>> @@ -434,25 +435,34 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const u8 *buf, size_t bufsiz,
>> * A positive number for a TPM error.
>> */
>> ssize_t tpm_transmit_cmd(struct tpm_chip *chip, const void *cmd,
>> - int len, unsigned int flags, const char *desc)
>> + size_t cmd_length, size_t min_rx_length,
>> + unsigned int flags, const char *desc)
>> {
>> const struct tpm_output_header *header;
>> int err;
>> + ssize_t len;
>>
>> - len = tpm_transmit(chip, (const u8 *)cmd, len, flags);
>> + len = tpm_transmit(chip, (const u8 *)cmd, cmd_length, flags);
>> if (len < 0)
>> return len;
>> else if (len < TPM_HEADER_SIZE)
>> return -EFAULT;
>>
>> header = cmd;
>> + if (len < be32_to_cpu(header->length))
>> + return -EFAULT;
>>
>> err = be32_to_cpu(header->return_code);
>> if (err != 0 && desc)
>> dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
>> desc);
>> + if (err)
>> + return err;
>>
>> - return err;
>> + if (be32_to_cpu(header->length) < min_rx_length)
>> + return -EFAULT;
>> +
>> + return 0;
>> }
>>
>> #define TPM_DIGEST_SIZE 20
>> @@ -468,7 +478,7 @@ static const struct tpm_input_header tpm_getcap_header = {
>> };
>>
>> ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
>> - const char *desc)
>> + const char *desc, size_t min_cap_length)
> tpm_getcap update should be its own commit.

tpm_getcap needs to pass something as min_rsp_body_length to
tpm_transmit_cmd. What would it pass?


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