On Thu, Mar 31, 2022 at 12:32:24PM +0300, Heikki Krogerus wrote: > 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@xxxxxxxxxxxxxxx> > > > Suggested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > Signed-off-by: Won Chung <wonchung@xxxxxxxxxx> > > > Cc: stable@xxxxxxxxxxxxxxx > > > > 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@xxxxxxxxxxxxxxx" > > > > > > Changes from v1: > > > - Add "Fixes" tag > > > - Send to stable@xxxxxxxxxxxxxxx > > > > > > 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. And going off of the driver name is sane? That feels ripe for bugs and problems in the future, but hey, I don't understand the need for this driver to care about another driver at all. And why is a USB device being passed to something that it thinks is a PCI device? That too feels really wrong and ripe for problems. thanks, greg k-h