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tpm: use try_get_ops() in tpm-space.c 

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>
This commit is contained in:
James Bottomley 2022-03-07 15:58:03 -05:00 committed by Jarkko Sakkinen
parent 590bfb57b2
commit fb5abce6b2
1 changed files with 4 additions and 4 deletions
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8
drivers/char/tpm/tpm2-space.c
View File

@ -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);
kfree(space->context_buf);
kfree(space->session_buf);
}