linux-kernel - [PATCH 4.19 40/67] usb: typec: ucsi: Clear PPM capability data in ucsi

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Message-Id: <20210614102645.136124651@linuxfoundation.org>
Date:   Mon, 14 Jun 2021 12:27:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Mayank Rana <mrana@...eaurora.org>,
        Jack Pham <jackp@...eaurora.org>
Subject: [PATCH 4.19 40/67] usb: typec: ucsi: Clear PPM capability data in ucsi_init() error path

From: Mayank Rana <mrana@...eaurora.org>

commit f247f0a82a4f8c3bfed178d8fd9e069d1424ee4e upstream.

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@...r.kernel.org
Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Mayank Rana <mrana@...eaurora.org>
Signed-off-by: Jack Pham <jackp@...eaurora.org>
Link: https://lore.kernel.org/r/20210609073535.5094-1-jackp@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/usb/typec/ucsi/ucsi.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -735,6 +735,7 @@ err_unregister:
 	}

 err_reset:
+	memset(&ucsi->cap, 0, sizeof(ucsi->cap));
 	ucsi_reset_ppm(ucsi);
 err:
 	mutex_unlock(&ucsi->ppm_lock);