Commit 933bfc5ad213 introduced the use of a locality counter to control when a locality request is allowed to be sent to the TPM. In the commit, the counter is indiscriminately decremented. Thus creating a situation for an integer underflow of the counter.
Signed-off-by: Daniel P. Smith <[email protected]> Signed-off-by: Ross Philipson <[email protected]> Reported-by: Kanth Ghatraju <[email protected]> Fixes: 933bfc5ad213 ("tpm, tpm: Implement usage counter for locality") --- drivers/char/tpm/tpm_tis_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 1b350412d8a6..4176d3bd1f04 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -180,7 +180,8 @@ static int tpm_tis_relinquish_locality(struct tpm_chip *chip, int l) struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); mutex_lock(&priv->locality_count_mutex); - priv->locality_count--; + if (priv->locality_count > 0) + priv->locality_count--; if (priv->locality_count == 0) __tpm_tis_relinquish_locality(priv, l); mutex_unlock(&priv->locality_count_mutex); -- 2.30.2
