linux-kernel - [PATCH v2] platform/chrome: cros_ec

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Date:   Wed,  7 Dec 2022 09:39:40 +0000
From:   Victor Ding <victording@...omium.org>
To:     linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev
Cc:     pmalani@...omium.org, groeck@...omium.org, dustin@...ett.net,
        gustavoars@...nel.org, gregkh@...uxfoundation.org,
        sebastian.reichel@...labora.com, dnojiri@...omium.org,
        lee.jones@...aro.org, bleung@...omium.org,
        tinghan.shen@...iatek.com, tzungbi@...nel.org,
        Victor Ding <victording@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Subject: [PATCH v2] platform/chrome: cros_ec_typec: zero out stale pointers

`cros_typec_get_switch_handles` allocates four pointers when obtaining
type-c switch handles. These pointers are all freed if failing to obtain
any of them; therefore, pointers in `port` become stale. The stale
pointers eventually cause use-after-free or double free in later code
paths. Zeroing out all pointer fields after freeing to eliminate these
stale pointers.

Fixes: f28adb41dab4 ("platform/chrome: cros_ec_typec: Register Type C switches")
Fixes: 1a8912caba02 ("platform/chrome: cros_ec_typec: Get retimer handle")
Signed-off-by: Victor Ding <victording@...omium.org>
---

Changes in v2:
- Updated commit messages;
- No code changes.

 drivers/platform/chrome/cros_ec_typec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
index 2a7ff14dc37e..59de4ce01fab 100644
--- a/drivers/platform/chrome/cros_ec_typec.c
+++ b/drivers/platform/chrome/cros_ec_typec.c
@@ -173,10 +173,13 @@ static int cros_typec_get_switch_handles(struct cros_typec_port *port,
 
 role_sw_err:
 	typec_switch_put(port->ori_sw);
+	port->ori_sw = NULL;
 ori_sw_err:
 	typec_retimer_put(port->retimer);
+	port->retimer = NULL;
 retimer_sw_err:
 	typec_mux_put(port->mux);
+	port->mux = NULL;
 mux_err:
 	return -ENODEV;
 }
-- 
2.39.0.rc0.267.gcb52ba06e7-goog