In the Linux kernel, the following vulnerability has been resolved: iommu/arm-smmu: Defer probe of clients after smmu device bound Null pointer dereference occurs due to a race between smmu driver probe and client driver probe, when ofdmaconfigure() for client is called after the iommudeviceregister() for smmu driver probe has executed but before the driverbound() for smmu driver has been called. Following is how the race occurs: T1:Smmu device probe T2: Client device probe reallyprobe() armsmmudeviceprobe() iommudeviceregister() reallyprobe() platformdmaconfigure() ofdmaconfigure() ofdmaconfigureid() ofiommuconfigure() iommuprobedevice() iommuinitdevice() armsmmuprobedevice() armsmmugetbyfwnode() driverfinddevicebyfwnode() driverfinddevice() nextdevice() klistnext() /* null ptr assigned to smmu / / null ptr dereference while smmu->streamidmask */ driverbound() klistaddtail() When this null smmu pointer is dereferenced later in armsmmuprobe_device, the device crashes. Fix this by deferring the probe of the client device until the smmu device has bound to the arm smmu driver. [will: Add comment]