[PATCH v2 3/3] tpm: in tpm2_del_space check if ops pointer is still valid
From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Date: 2021-02-02 22:12:16
Also in:
lkml
Subsystem:
the rest, tpm device driver · Maintainers:
Linus Torvalds, Peter Huewe, Jarkko Sakkinen
From: Lino Sanfilippo <redacted> 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 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 <redacted> --- 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