Messages in this thread | | | Subject | Re: [patch 1/2] Validate itimer timeval from userspace | From | Thomas Gleixner <> | Date | Sat, 18 Mar 2006 21:38:51 +0100 |
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On Sat, 2006-03-18 at 12:31 -0800, Andrew Morton wrote: > Thomas Gleixner <tglx@linutronix.de> wrote: > > > > On Sat, 2006-03-18 at 12:07 -0800, Andrew Morton wrote: > > > > > From my reading, 2.4's sys_setitimer() will normalise the incoming timeval > > > rather than rejecting it. And I think 2.6.13 did that too. > > > > > > It would be bad of us to change this behaviour, even if that's what the > > > spec says we should do - because we can break existing applications. > > > > > > So I think we're stuck with it - we should normalise and then accept such > > > timevals. And we should have a big comment explaining how we differ from > > > the spec, and why. > > > > Hmm. How do you treat a negative value ? > > > > In the same way as earlier kernels did! > > Unless, of course, those kernels did something utterly insane. In that > case we'd need to have a little think.
It was caught by:
timeval_to_jiffies(const struct timeval *value) { unsigned long sec = value->tv_sec; long usec = value->tv_usec;
if (sec >= MAX_SEC_IN_JIFFIES) sec = MAX_SEC_IN_JIFFIES; .... }
The conversion of long to unsigned long converted a negative value to the maximum timeout.
It's not utterly insane, but it does not make much sense either.
Of course I can convert it that way, if we want to keep this "help sloppy programmers aid" alive.
tglx
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