linux-kernel - Re: [PATCH v2] misc/mei: Add NULL check to component match callback functions

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Date:   Thu, 31 Mar 2022 01:39:47 -0700
From:   Won Chung <wonchung@...gle.com>
To:     Tomas Winkler <tomas.winkler@...el.com>
Cc:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Benson Leung <bleung@...omium.org>,
        Prashant Malani <pmalani@...omium.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2] misc/mei: Add NULL check to component match callback functions

Hi,

I need to resend v3 with flags corrected. Sorry for confusion.

Won

On Wed, Mar 30, 2022 at 2:17 PM Won Chung <wonchung@...gle.com> wrote:
>
> Component match callback functions need to check if expected data is
> passed to them. Without this check, it can cause a NULL pointer
> dereference when another driver registers a component before i915
> drivers have their component master fully bind.
>
> Fixes: 1e8d19d9b0dfc ("mei: hdcp: bind only with i915 on the same PCH")
> Fixes: c2004ce99ed73 ("mei: pxp: export pavp client to me client bus")
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Won Chung <wonchung@...gle.com>
> ---
> Changes from v1:
> - Add "Fixes" tag
> - Send to stable@...r.kernel.org
>
>  drivers/misc/mei/hdcp/mei_hdcp.c | 2 +-
>  drivers/misc/mei/pxp/mei_pxp.c   | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
> index ec2a4fce8581..843dbc2b21b1 100644
> --- a/drivers/misc/mei/hdcp/mei_hdcp.c
> +++ b/drivers/misc/mei/hdcp/mei_hdcp.c
> @@ -784,7 +784,7 @@ static int mei_hdcp_component_match(struct device *dev, int subcomponent,
>  {
>         struct device *base = data;
>
> -       if (strcmp(dev->driver->name, "i915") ||
> +       if (!base || !dev->driver || strcmp(dev->driver->name, "i915") ||
>             subcomponent != I915_COMPONENT_HDCP)
>                 return 0;
>
> diff --git a/drivers/misc/mei/pxp/mei_pxp.c b/drivers/misc/mei/pxp/mei_pxp.c
> index f7380d387bab..e32a81da8af6 100644
> --- a/drivers/misc/mei/pxp/mei_pxp.c
> +++ b/drivers/misc/mei/pxp/mei_pxp.c
> @@ -131,7 +131,7 @@ static int mei_pxp_component_match(struct device *dev, int subcomponent,
>  {
>         struct device *base = data;
>
> -       if (strcmp(dev->driver->name, "i915") ||
> +       if (!base || !dev->driver || strcmp(dev->driver->name, "i915") ||
>             subcomponent != I915_COMPONENT_PXP)
>                 return 0;
>
> --
> 2.35.1.1021.g381101b075-goog
>