[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH] tpm: use try_get_ops() in tpm-space.c
As part of the series conversion to remove nested TPM operations:

exposure of the chip->tpm_mutex was removed from much of the upper
level code. In this conversion, tpm2_del_space() was missed. This
didn't matter much because it's usually called closely after a
converted operation, so there's only a very tiny race window where the
chip can be removed before the space flushing is done which causes a
NULL deref on the mutex. However, there are reports of this window
being hit in practice, so fix this by converting tpm2_del_space() to
use tpm_try_get_ops(), which performs all the teardown checks before
acquring the mutex.

Signed-off-by: James Bottomley <>
Reviewed-by: Jarkko Sakkinen <>
drivers/char/tpm/tpm2-space.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 265ec72b1d81..ffb35f0154c1 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -58,12 +58,12 @@ 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)) {
+ if (tpm_try_get_ops(chip) == 0) {
tpm2_flush_sessions(chip, space);
- tpm_chip_stop(chip);
+ tpm_put_ops(chip);
- mutex_unlock(&chip->tpm_mutex);

 \ /
  Last update: 2022-03-07 21:59    [W:0.045 / U:0.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site