Re: [PATCH v2] HID: intel-ish-hid: Fix kernel panic during warm reset

[Jiri Kosina]

On Mon, 27 Mar 2023, Tanu Malhotra wrote:

> During warm reset device->fw_client is set to NULL. If a bus driver is
> registered after this NULL setting and before new firmware clients are
> enumerated by ISHTP, kernel panic will result in the function
> ishtp_cl_bus_match(). This is because of reference to
> device->fw_client->props.protocol_name.
> 
> ISH firmware after getting successfully loaded, sends a warm reset
> notification to remove all clients from the bus and sets
> device->fw_client to NULL. Until kernel v5.15, all enabled ISHTP kernel
> module drivers were loaded right after any of the first ISHTP device was
> registered, regardless of whether it was a matched or an unmatched
> device. This resulted in all drivers getting registered much before the
> warm reset notification from ISH.
> 
> Starting kernel v5.16, this issue got exposed after the change was
> introduced to load only bus drivers for the respective matching devices.
> In this scenario, cros_ec_ishtp device and cros_ec_ishtp driver are
> registered after the warm reset device fw_client NULL setting.
> cros_ec_ishtp driver_register() triggers the callback to
> ishtp_cl_bus_match() to match ISHTP driver to the device and causes kernel
> panic in guid_equal() when dereferencing fw_client NULL pointer to get
> protocol_name.
> 
> Fixes: f155dfeaa4ee ("platform/x86: isthp_eclite: only load for matching devices")
> Fixes: facfe0a4fdce ("platform/chrome: chros_ec_ishtp: only load for matching devices")
> Fixes: 0d0cccc0fd83 ("HID: intel-ish-hid: hid-client: only load for matching devices")
> Fixes: 44e2a58cb880 ("HID: intel-ish-hid: fw-loader: only load for matching devices")
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.16+
> Signed-off-by: Tanu Malhotra <tanu.malhotra@xxxxxxxxx>
> Tested-by: Shaunak Saha <shaunak.saha@xxxxxxxxx>
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>

Applied, thank you.

-- 
Jiri Kosina
SUSE Labs