On Tue, Feb 02, 2021 at 11:09:03PM +0100, Lino Sanfilippo wrote:
> From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
>
> In tpm2_del_space() the sessions are flushed by means of the tpm_chip
> operations. However the concerning operations pointer my already be NULL at
~~
may
What is "concerniog operations"? Unfamiliar term. Maybe just consistently
se chip->ops? Now you have also "tpm_chip operations" and chip->ops, in
addition to "concerning operations" in one paragraph commit message.
> this time in case that the chip has been unregistered (see
> tpm_chip_unregister() which calls tpm_del_char_device() which sets
> chip->ops to NULL).
> Before accessing chip->ops check if it is still valid. Skip flushing
> the sessions in this case.
>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Instead of cross referencing please describe the scenario (i.e.
the sequence of operations) of failure.
Fixes tag is also missing.
> ---
> drivers/char/tpm/tpm2-space.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
> index 784b8b3..9a29a40 100644
> --- a/drivers/char/tpm/tpm2-space.c
> +++ b/drivers/char/tpm/tpm2-space.c
> @@ -58,12 +58,17 @@ int tpm2_init_space(struct tpm_space *space, unsigned int buf_size)
>
> void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space)
> {
> - mutex_lock(&chip->tpm_mutex);
> - if (!tpm_chip_start(chip)) {
> - tpm2_flush_sessions(chip, space);
> - tpm_chip_stop(chip);
> + down_read(&chip->ops_sem);
> + if (chip->ops) {
> + mutex_lock(&chip->tpm_mutex);
> + if (!tpm_chip_start(chip)) {
> + tpm2_flush_sessions(chip, space);
> + tpm_chip_stop(chip);
> + }
> + mutex_unlock(&chip->tpm_mutex);
> }
> - mutex_unlock(&chip->tpm_mutex);
> + up_read(&chip->ops_sem);
> +
> kfree(space->context_buf);
> kfree(space->session_buf);
> }
> --
> 2.7.4
>
/Jarkko
