ucsi_init() which runs from a workqueue sets ucsi->connector and on an error will clear it again.

ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed.

ucsi_init() setting ucsi->connector and then clearing it again on an error creates a race where the check in the consumers may pass, only to have ucsi->connector free-ed underneath them when ucsi_init() hits an error.

Fix this race by making ucsi_init() store the connector array in a local variable and only assign it to ucsi->connector on success.

Fixes: bdc62f2bae8f ("usb: typec: ucsi: Simplified registration and I/O API") Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede hdegoede@redhat.com --- drivers/usb/typec/ucsi/ucsi.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c index e762897cb25a..796ae230c60b 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1045,9 +1045,8 @@ static struct fwnode_handle *ucsi_find_fwnode(struct ucsi_connector *con) return NULL; }

-static int ucsi_register_port(struct ucsi *ucsi, int index) +static int ucsi_register_port(struct ucsi *ucsi, int index, struct ucsi_connector *con) { - struct ucsi_connector *con = &ucsi->connector[index]; struct typec_capability *cap = &con->typec_cap; enum typec_accessory *accessory = cap->accessory; enum usb_role u_role = USB_ROLE_NONE; @@ -1210,7 +1209,7 @@ static int ucsi_register_port(struct ucsi *ucsi, int index) */ static int ucsi_init(struct ucsi *ucsi) { - struct ucsi_connector *con; + struct ucsi_connector *con, *connector; u64 command; int ret; int i; @@ -1241,16 +1240,15 @@ static int ucsi_init(struct ucsi *ucsi) }

/* Allocate the connectors. Released in ucsi_unregister() */ - ucsi->connector = kcalloc(ucsi->cap.num_connectors + 1, - sizeof(*ucsi->connector), GFP_KERNEL); - if (!ucsi->connector) { + connector = kcalloc(ucsi->cap.num_connectors + 1, sizeof(*connector), GFP_KERNEL); + if (!connector) { ret = -ENOMEM; goto err_reset; }

/* Register all connectors */ for (i = 0; i < ucsi->cap.num_connectors; i++) { - ret = ucsi_register_port(ucsi, i); + ret = ucsi_register_port(ucsi, i, &connector[i]); if (ret) goto err_unregister; } @@ -1262,10 +1260,11 @@ static int ucsi_init(struct ucsi *ucsi) if (ret < 0) goto err_unregister;

+ ucsi->connector = connector; return 0;

err_unregister: - for (con = ucsi->connector; con->port; con++) { + for (con = connector; con->port; con++) { ucsi_unregister_partner(con); ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON); ucsi_unregister_port_psy(con); @@ -1274,10 +1273,7 @@ static int ucsi_init(struct ucsi *ucsi) typec_unregister_port(con->port); con->port = NULL; } - - kfree(ucsi->connector); - ucsi->connector = NULL; - + kfree(connector); err_reset: memset(&ucsi->cap, 0, sizeof(ucsi->cap)); ucsi_reset_ppm(ucsi);

On Tue, Feb 28, 2023 at 10:03:03AM +0100, Hans de Goede wrote:

When ucsi_init() fails, ucsi->connector is NULL, yet in case of ucsi_acpi we may still get events which cause the ucs_acpi code to call ucsi_connector_change(), which then derefs the NULL ucsi->connector pointer.

Fix this by adding a check for ucsi->connector being NULL, as is already done in ucsi_resume() for similar reasons.

Fixes: bdc62f2bae8f ("usb: typec: ucsi: Simplified registration and I/O API") Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede hdegoede@redhat.com

---

drivers/usb/typec/ucsi/ucsi.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c index 1cf8947c6d66..e762897cb25a 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -842,7 +842,13 @@ static void ucsi_handle_connector_change(struct work_struct *work) */ void ucsi_connector_change(struct ucsi *ucsi, u8 num) {

• struct ucsi_connector *con = &ucsi->connector[num - 1];

• struct ucsi_connector *con;
• /* Check for ucsi_init() failure */
• if (!ucsi->connector)

• return;
  

• con = &ucsi->connector[num - 1];

What prevents ->connector from changing to NULL right after you check this and before you dereference it again?

thanks,

greg k-h