Hi Richard, On Wed, Oct 08, 2014 at 10:49:29PM +0200, Richard Leitner wrote: > Hi, > currently I discovered the possibility that device file numbers of the input > subsystem could go negative when the signed int "border" is passed. To fix > this behaviour I sent a patch a few minutes ago. > > But as the subject says there is currently the (theoretical) possibility that > the same input device file name is given out twice. This can happen if the > "input_no" variable had an overflow (due to the fact this is at least at 2^32 > I call the issue theoretical). If such a case occurs a -EEXISTS is returned at > the creation of the file. > > IMHO it would be a good idea to check if the chosen input device file name > is valid at the point it is created (which is currently input_allocate_device). > So you can just increment and check it again until there's a valid number/name > found for it. > > I'm pretty new to the input subsystem, so what do you think about it? > Any comments/ideas? Would there be a better place to do such checking? I do not think it is worth checking. Yes, theoretically you can wrap around, but practically instantiating at least 2^32 devices will take too long. If ever it becomes a concern my very distant future relatives will move the counter to 64 or 128 bit and call it a day. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
