| From fb5abce6b2bb5cb3d628aaa63fa821da8c4600f9 Mon Sep 17 00:00:00 2001 |
| From: James Bottomley <James.Bottomley@HansenPartnership.com> |
| Date: Mon, 7 Mar 2022 15:58:03 -0500 |
| Subject: tpm: use try_get_ops() in tpm-space.c |
| |
| From: James Bottomley <James.Bottomley@HansenPartnership.com> |
| |
| commit fb5abce6b2bb5cb3d628aaa63fa821da8c4600f9 upstream. |
| |
| As part of the series conversion to remove nested TPM operations: |
| |
| https://lore.kernel.org/all/20190205224723.19671-1-jarkko.sakkinen@linux.intel.com/ |
| |
| 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. |
| |
| Cc: stable@vger.kernel.org # 5.4.x |
| Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> |
| Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> |
| Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/char/tpm/tpm2-space.c | 8 ++++---- |
| 1 file changed, 4 insertions(+), 4 deletions(-) |
| |
| --- 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 *sp |
| |
| 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); |
| + |
| kfree(space->context_buf); |
| kfree(space->session_buf); |
| } |