[PATCH] usb: typec: ucsi: Clear PPM capability data in ucsi_init() error path

From: Mayank Rana <redacted>

If ucsi_init() fails for some reason (e.g. ucsi_register_port()
fails or general communication failure to the PPM), particularly at
any point after the GET_CAPABILITY command had been issued, this
results in unwinding the initialization and returning an error.
However the ucsi structure's ucsi_capability member retains its
current value, including likely a non-zero num_connectors.
And because ucsi_init() itself is done in a workqueue a UCSI
interface driver will be unaware that it failed and may think the
ucsi_register() call was completely successful.  Later, if
ucsi_unregister() is called, due to this stale ucsi->cap value it
would try to access the items in the ucsi->connector array which
might not be in a proper state or not even allocated at all and
results in NULL or invalid pointer dereference.

Fix this by clearing the ucsi->cap value to 0 during the error
path of ucsi_init() in order to prevent a later ucsi_unregister()
from entering the connector cleanup loop.

Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
Cc: stable@vger.kernel.org
Signed-off-by: Mayank Rana <redacted>
Signed-off-by: Jack Pham <redacted>
---
 drivers/usb/typec/ucsi/ucsi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index b433169ef6fa..b7d104c80d85 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c

@@ -1253,6 +1253,7 @@ static int ucsi_init(struct ucsi *ucsi)
 	}
 
 err_reset:
+	memset(&ucsi->cap, 0, sizeof(ucsi->cap));
 	ucsi_reset_ppm(ucsi);
 err:
 	return ret;

-- 
2.24.0

On Wed, Jun 09, 2021 at 12:35:35AM -0700, Jack Pham wrote:

From: Mayank Rana <redacted>

If ucsi_init() fails for some reason (e.g. ucsi_register_port()
fails or general communication failure to the PPM), particularly at
any point after the GET_CAPABILITY command had been issued, this
results in unwinding the initialization and returning an error.
However the ucsi structure's ucsi_capability member retains its
current value, including likely a non-zero num_connectors.
And because ucsi_init() itself is done in a workqueue a UCSI
interface driver will be unaware that it failed and may think the
ucsi_register() call was completely successful.  Later, if
ucsi_unregister() is called, due to this stale ucsi->cap value it
would try to access the items in the ucsi->connector array which
might not be in a proper state or not even allocated at all and
results in NULL or invalid pointer dereference.

Fix this by clearing the ucsi->cap value to 0 during the error
path of ucsi_init() in order to prevent a later ucsi_unregister()
from entering the connector cleanup loop.

Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
Cc: stable@vger.kernel.org
Signed-off-by: Mayank Rana <redacted>
Signed-off-by: Jack Pham <redacted>

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

-- 
heikki