On Thu, Mar 31, 2022 at 11:00:46AM +0200, Greg KH wrote:
On Thu, Mar 31, 2022 at 08:49:18AM +0000, Won Chung 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.
How can that happen in a real system? Or does this just happen for when you are doing development and testing?
Fixes: 1e8d19d9b0dfc ("mei: hdcp: bind only with i915 on the same PCH") Fixes: c2004ce99ed73 ("mei: pxp: export pavp client to me client bus") Suggested-by: Heikki Krogerus heikki.krogerus@linux.intel.com Suggested-by: Mika Westerberg mika.westerberg@linux.intel.com Signed-off-by: Won Chung wonchung@google.com Cc: stable@vger.kernel.org
Why does this need to go to stable? How can this be triggered in older kernels?
Changes from v2:
- Correctly add "Suggested-by" tag
- Add "Cc: stable@vger.kernel.org"
Changes from v1:
- Add "Fixes" tag
- Send to stable@vger.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") ||
How can base be NULL?
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") ||
Same here, shouldn't this be caught by the driver core or bus and match should not be called?
Why not fix this in the component/driver core instead?
A component is just a device that is declared to be a "component", and the code that declares it as component does not have to be the driver of that device. You simply can't assume that it's bind to a driver like this function does.
In our case the "components" are USB ports, so devices that are never bind to drivers.
thanks,