From: Lino Sanfilippo l.sanfilippo@kunbus.com
In tpm2_del_space() chip->ops is used for flushing the sessions. However this function may be called after tpm_chip_unregister() which sets the chip->ops pointer to NULL. Avoid a possible NULL pointer dereference by checking if chip->ops is still valid before accessing it.
Fixes: a3fbfae82b4c ("tpm: take TPM chip power gating out of tpm_transmit()") Signed-off-by: Lino Sanfilippo l.sanfilippo@kunbus.com --- 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); }