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    Subject[PATCH 4.4 01/97] tpm: fix potential buffer overruns caused by bit glitches on the bus
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

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

    From: Jeremy Boone <jeremy.boone@nccgroup.trust>

    commit 3be23274755ee85771270a23af7691dc9b3a95db upstream.

    Discrete TPMs are often connected over slow serial buses which, on
    some platforms, can have glitches causing bit flips. If a bit does
    flip it could cause an overrun if it's in one of the size parameters,
    so sanity check that we're not overrunning the provided buffer when
    doing a memcpy().

    Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
    Cc: stable@vger.kernel.org
    Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
    Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Signed-off-by: James Morris <james.morris@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/char/tpm/tpm-interface.c | 5 +++++
    drivers/char/tpm/tpm2-cmd.c | 6 ++++++
    2 files changed, 11 insertions(+)

    --- a/drivers/char/tpm/tpm-interface.c
    +++ b/drivers/char/tpm/tpm-interface.c
    @@ -1040,6 +1040,11 @@ int tpm_get_random(u32 chip_num, u8 *out
    break;

    recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
    + if (recd > num_bytes) {
    + total = -EFAULT;
    + break;
    + }
    +
    memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);

    dest += recd;
    --- a/drivers/char/tpm/tpm2-cmd.c
    +++ b/drivers/char/tpm/tpm2-cmd.c
    @@ -622,6 +622,11 @@ static int tpm2_unseal_cmd(struct tpm_ch
    if (!rc) {
    data_len = be16_to_cpup(
    (__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
    + if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE + 1) {
    + rc = -EFAULT;
    + goto out;
    + }
    +
    data = &buf.data[TPM_HEADER_SIZE + 6];

    memcpy(payload->key, data, data_len - 1);
    @@ -629,6 +634,7 @@ static int tpm2_unseal_cmd(struct tpm_ch
    payload->migratable = data[data_len - 1];
    }

    +out:
    tpm_buf_destroy(&buf);
    return rc;
    }

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