mangler@cit-vax.Caltech.Edu (System Mangler) (05/26/87)
Most drivers check that minor(dev) is within range in every call to the read and write routines. Why isn't it sufficient to do this once in the open routine? Is it just unwarranted paranoia? Don Speck speck@vlsi.caltech.edu {seismo,rutgers,ames}!cit-vax!speck
mouse@mcgill-vision.UUCP (06/07/87)
In article <2814@cit-vax.Caltech.Edu>, mangler@cit-vax.Caltech.Edu (System Mangler) writes: > Most drivers check that minor(dev) is within range in every call to > the read and write routines. Why isn't it sufficient to do this once > in the open routine? Is it just unwarranted paranoia? I would say yes, it is just paranoia. I would not say it is really unwarranted. (I am assuming the device does really have an open routine which does check the unit number - a few simple devices just have nulldev() for an open routine.) The check is cheap, and the potential for harm is great (scribbling on basically random parts of kernel memory...). der Mouse (mouse@mcgill-vision.uucp)