linux-kernel - [PATCH] usb: typec: fix potential out of bounds in ucsi_ccg_update_set_new_cam

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Message-ID: <325102b3-eaa8-4918-a947-22aca1146586@stanley.mountain>
Date: Mon, 4 Nov 2024 20:16:42 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Ajay Gupta <ajayg@...dia.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	Haotien Hsu <haotienh@...dia.com>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] usb: typec: fix potential out of bounds in
 ucsi_ccg_update_set_new_cam_cmd()

The "*cmd" variable can be controlled by the user via debugfs.  That means
"new_cam" can be as high as 255 while the size of the uc->updated[] array
is UCSI_MAX_ALTMODES (30).

The call tree is:
ucsi_cmd() // val comes from simple_attr_write_xsigned()
-> ucsi_send_command()
   -> ucsi_send_command_common()
      -> ucsi_run_command() // calls ucsi->ops->sync_control()
         -> ucsi_ccg_sync_control()

Fixes: 170a6726d0e2 ("usb: typec: ucsi: add support for separate DP altmode devices")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/usb/typec/ucsi/ucsi_ccg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
index ba58d11907bc..bccfc03b5986 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -482,6 +482,8 @@ static void ucsi_ccg_update_set_new_cam_cmd(struct ucsi_ccg *uc,
 
 	port = uc->orig;
 	new_cam = UCSI_SET_NEW_CAM_GET_AM(*cmd);
+	if (new_cam >= ARRAY_SIZE(uc->updated))
+		return;
 	new_port = &uc->updated[new_cam];
 	cam = new_port->linked_idx;
 	enter_new_mode = UCSI_SET_NEW_CAM_ENTER(*cmd);
-- 
2.45.2