On Thu, 2012-12-27 at 08:12 -0600, Asim Kadav wrote: > > If your theory is that the hardware just returned a bogus value, this > > isn't the right way to sanitise it because the chances are you'll > > complete the wrong command and cause corruption: you'd have to halt the > > entire system at that point. Also, I don't understand why you think the > > value should only be 0-31? The size of variable allocated there is for > > SCBs up to 243, no idea why, since some of the allocation routines will > > search up to 256. However, safety from overrun should be guaranteed at > > least at the system level by the can_queue value. > > I agree. If the hardware returns a bogus value, it immediately would crash. > Would a more appropriate patch be checking within the ORC_MAXQUEUE > range and flagging an error? It's probably really not worth it. The u100w2 is a pretty old SCSI driver. I can't imagine there's more than a handful of them left. As I said, there's no evidence of a problem. > > Double checking hardware values isn't something we habitually do unless > > there's a known reason for it (like the state machine does throw bogus > > values with a defined recovery procedure). We definitely don't run in > > the mode where you can't trust your hardware. > > > > Hardware can fail for multiple reasons. Furthermore, such bugs are security > vulnerabilities too in the case of virtual hardware or USB drivers where > such values can be faked. The article in my patch gives more details. > http://lwn.net/Articles/479653/ USB possibly, but this isn't a USB driver. Virtual hardware is a bit unlikely, since it's created by the host for the guest. I don't believe there's any hypervisor system that can survive attempted subversion by the *host* (host protecting against guest, yes, but guest trying to protect against host is a very different ball game). James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
