Messages in this thread | | | Date | Wed, 26 Jan 2005 17:06:20 +0100 | From | Sytse Wielinga <> | Subject | Re: thoughts on kernel security issues |
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On Tue, Jan 25, 2005 at 03:03:04PM -0500, John Richard Moser wrote: > That being said, you should also consider (unless somebody forgot to > tell me something) that it takes two source trees to make a split-out > patch. The author also has to chew down everything but the feature he > wants to split out. I could probably log 10,000 man-hours splitting up > GrSecurity. :)
I'd try out Andrew's patch scripts if I were you. If you're making a patch to the kernel, you'd best keep it in separate patches from the beginning, and that's exactly what those scripts are very useful for.
> > It's also a lot easier to find the (inevitable) bugs. Either you already > > have a clue ("try reverting that one patch") or you can do things like > > binary searching. The bugs introduced a patch often have very little to do > > with the thing a patch fixes - exactly because the patch _fixes_ > > something, it's been tested with that particular problem, and the new > > problem it introduces is usually orthogonal. > > true. Very very true. > > With things like Gr, there's like a million features. Normally the > first step I take is "Disable it all". If it still breaks, THEN THERE'S > A PROBLEM. If it works, then the binary searching begins.
So how do you think you would do a binary search within big patches, if it would take you 10,000 man-hours to split up the patch? Disabling a lot of small patches is easy, disabling a part of a big one takes a lot more work.
> > Which is why lots of small patches usually have _different_ bug behaviour > > than the patch they fix. To go back to the A+B fix: the bug they fix may > > be fixed only by the _combination_ of the patch, but the bug they cause is > > often an artifact of _one_ of the patches. > > > > Wasn't talking about bugfixes, see above.
Oh, so you're saying that security fixes don't cause bugs? Great world you live in, then...
> > IOW, splitting the patches up makes them > > - easier to merge > > - easier to verify > > - easier to debug > > > > and combining them has _zero_ advantages (whatever bug the combined patch > > fix _will_ be fixed by the series of individual patches too - even if the > > splitting was buggy in some respect, you are pretty much guaranteed of > > this, since the bug you were trying to fix is the _one_ thing you are > > really testing for). > > Lots of work to split up a patch though.
See above.
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