Re: Kasan crash in hid-steam

[Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>]

Hi, thank you for the report.

It looks like using uhid you exercised some codepath that are never seen
using the real HW. And that exposes some race handling the list of
devices.

Please, see if the following patch fixes the issue.
Best regards.

---
 drivers/hid/hid-steam.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
index 6286204d4c56..a3b151b29bd7 100644
--- a/drivers/hid/hid-steam.c
+++ b/drivers/hid/hid-steam.c
@@ -526,7 +526,8 @@ static int steam_register(struct steam_device *steam)
                        steam_battery_register(steam);

                mutex_lock(&steam_devices_lock);
-               list_add(&steam->list, &steam_devices);
+               if (list_empty(&steam->list))
+                       list_add(&steam->list, &steam_devices);
                mutex_unlock(&steam_devices_lock);
        }

@@ -552,7 +553,7 @@ static void steam_unregister(struct steam_device *steam)
                hid_info(steam->hdev, "Steam Controller '%s' disconnected",
                                steam->serial_no);
                mutex_lock(&steam_devices_lock);
-               list_del(&steam->list);
+               list_del_init(&steam->list);
                mutex_unlock(&steam_devices_lock);
                steam->serial_no[0] = 0;
        }
@@ -738,6 +739,7 @@ static int steam_probe(struct hid_device *hdev,
        mutex_init(&steam->mutex);
        steam->quirks = id->driver_data;
        INIT_WORK(&steam->work_connect, steam_work_connect_cb);
+       INIT_LIST_HEAD(&steam->list);

        steam->client_hdev = steam_create_client_hid(hdev);
        if (IS_ERR(steam->client_hdev)) {
--
2.27.0