Re: [Qemu-devel] [PATCH 0/4] migration: fix CVE-2014-7840

[Michael S. Tsirkin]

On Mon, Nov 17, 2014 at 05:50:34PM +0530, Amit Shah wrote:
> On (Mon) 17 Nov 2014 [13:48:58], Michael S. Tsirkin wrote:
> > On Mon, Nov 17, 2014 at 04:37:50PM +0530, Amit Shah wrote:
> > > On (Mon) 17 Nov 2014 [12:52:59], Michael S. Tsirkin wrote:
> > > > On Mon, Nov 17, 2014 at 04:08:58PM +0530, Amit Shah wrote:
> > > > > On (Mon) 17 Nov 2014 [12:32:57], Michael S. Tsirkin wrote:
> > > > > > On Mon, Nov 17, 2014 at 12:06:38PM +0530, Amit Shah wrote:
> > > > > > > On (Wed) 12 Nov 2014 [11:44:35], Michael S. Tsirkin wrote:
> > > > > > > > This patchset fixes CVE-2014-7840: invalid
> > > > > > > > migration stream can cause arbitrary qemu memory
> > > > > > > > overwrite.
> > > > > > > > First patch includes the minimal fix for the issue.
> > > > > > > > Follow-up patches on top add extra checking to reduce the
> > > > > > > > chance this kind of bug recurs.
> > > > > > > > 
> > > > > > > > Note: these are already (tentatively-pending review)
> > > > > > > > queued in my tree, so only review/ack
> > > > > > > > is necessary.
> > > > > > > 
> > > > > > > Why not let this go in via the migration tree?
> > > > > > 
> > > > > > Well I Cc'd Juan and David, so if they had a problem with this, I 
> > > > > > expect
> > > > > > they'd complain.  David acked so I assume it's ok.  Since I wasted 
> > > > > > time
> > > > > > testing this and have it on my tree already, might as well just 
> > > > > > merge.
> > > > > 
> > > > > IMO asking as a courtesy would've been better than just stating it.
> > > > 
> > > > Right, thanks for reminding me.
> > > > 
> > > > BTW, there is actually a good reason to special-case it: it's a CVE fix,
> > > > which I handle.  So they stay on my private queue and are passed
> > > > to vendors so vendors can fix downstreams, until making fix public is
> > > > cleared with all reporters and vendors.
> > > > After reporting is cleared, I try to collect acks but don't normally 
> > > > route
> > > > patches through separate queues - that would make it harder to
> > > > track the status which we need for CVEs.
> > > 
> > > Patch is public, so all of this doesn't really matter.
> > > 
> > > But: involving maintainers in their areas, even if the patch is
> > > embargoed, should be a pre-requisite.  I'm not sure if we're doing
> > > that, but please do that so patches get a proper review from the
> > > maintainers.
> > 
> > Involving more people means more back and forth with reporters which
> > must approve any disclosure.  If the issue isn't clear, I do involve
> > maintainers.  I send patches on list and try to merge them only after
> > they get ack from relevant people. I'm sorry, but this is as far as I
> > have the time to go.
> 
> The other aspect of the thing is sub-optimal, or patches with bugs,
> get pushed in, because the maintainers didn't get involved.  

Patches don't get merged before they are on list for a while.
I typically ping people if I don't get acks.

> Also,
> maintainers don't like code being changed behind their backs...

no one is changing code in secret here.
So don't turn your back - review patches :0

FYI I'm sometimes merging patches on list that don't get reviews for
weeks - if they seem to make sense.

> But if you're overloaded with handling security issues, we can help
> identify a co-maintainer as well.

Sure. I don't think we need more process to slow down the flow of
patches even more.

> > > > I guess this specific one actually is well contained, so it could go in
> > > > through a specific tree if it had to.  In fact, it is still possible if
> > > > Juan says he prefers it so: I only expect to send pull request around
> > > > tomorrow or the day after that.
> > > 
> > > I'm sure we prefer migration patches go through the migration tree.
> > 
> > I'm sorry - I disagree. maintainer boundaries in qemu are quite flexible
> > because code is somewhat monolithic.  We prefer that patches are
> > reviewed by people that are familiar with it, that is for sure.  Which
> > tree is definitely secondary.  If there's a conflict, we can resolve it.
> > I doubt it will happen here.
> 
> For well-maintained areas, I'm not sure I agree with the flexibility
> argument.  Juan has been maintaining the migration tree for a long
> while now.

Did you look at the patches?
Most of them touch files like exec.c which is all over
the place.

> > > Also, this week I'm looking at the migration queue -- it's an
> > > unofficial split of maintenance duties between Juan and me while we're
> > > still trying to find out what works best.
> > > 
> > 
> > I don't know how am I supposed to know that.
> 
> Right now you don't need to -- I just pick patches up and pass them on
> to Juan, who does the pull req.
> 
> > Send patch to MAINTAINERS or something?
> 
> I'm going to add myself to migration maintainers, yes.  But that's
> secondary; the pull reqs still go via Juan.
> 
> 
>               Amit