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Message-ID: <c6b89edad5f74bf5ca82401a3d9cc5b4198baac8.camel@linux.intel.com>
Subject: Re: [PATCH] HID: intel-ish-hid: Fix kernel panic during warm reset
From:   srinivas pandruvada <srinivas.pandruvada@linux.intel.com>
To:     Tanu Malhotra <tanu.malhotra@intel.com>, jikos@kernel.org
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        even.xu@intel.com, Shaunak Saha <shaunak.saha@intel.com>
Date:   Mon, 27 Mar 2023 05:10:14 -0700
In-Reply-To: <20230327032310.2416272-1-tanu.malhotra@intel.com>
References: <20230327032310.2416272-1-tanu.malhotra@intel.com>
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On Sun, 2023-03-26 at 20:23 -0700, Tanu Malhotra wrote:

some minor nits below.

> 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.
>=20
> 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 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.
One paragraph break will be better.

>  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 driver to the device
> and
> causes kernel panic in guid_equal() when dereferencing fw_client NULL
> pointer to get protocol_name.
>=20
> 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")
>=20
No need of blank line.

> Signed-off-by: Tanu Malhotra <tanu.malhotra@intel.com>
> Tested-by: Shaunak Saha <shaunak.saha@intel.com>
You can also add=20
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>


Also add
Cc: <stable@vger.kernel.org> # 5.16+

> ---
When you submit "PATCH v2", Add change log here. (That is below "---").
Something like this:
v2
- Updated commit description
- Added CC to stable

> =C2=A0drivers/hid/intel-ish-hid/ishtp/bus.c | 4 ++--
> =C2=A01 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/hid/intel-ish-hid/ishtp/bus.c
> b/drivers/hid/intel-ish-hid/ishtp/bus.c
> index 81385ab37fa9..4f540906268f 100644
> --- a/drivers/hid/intel-ish-hid/ishtp/bus.c
> +++ b/drivers/hid/intel-ish-hid/ishtp/bus.c
> @@ -241,8 +241,8 @@ static int ishtp_cl_bus_match(struct device *dev,
> struct device_driver *drv)
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct ishtp_cl_device *d=
evice =3D to_ishtp_cl_device(dev);
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct ishtp_cl_driver *d=
river =3D to_ishtp_cl_driver(drv);
> =C2=A0
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return guid_equal(&driver->id[=
0].guid,
> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 &d=
evice->fw_client->props.protocol_name);
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return(device->fw_client ? gui=
d_equal(&driver->id[0].guid,
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 &device->fw_client-
> >props.protocol_name) : 0);
Align the second line to char "d" after "(".

Thanks,
Srinivas

> =C2=A0}
> =C2=A0
> =C2=A0/**