Date: Wed, 16 Jan 2002 21:17:12 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Alfred Perlstein <bright@mu.org>, "Alan L. Cox" <alc@imimic.com>, FreeBSD-hackers@FreeBSD.ORG, re@FreeBSD.ORG Subject: Re: Need review of NFS patch set for server .. missing/wrong vput() issues Message-ID: <200201162117.aa18236@salmon.maths.tcd.ie> In-Reply-To: Your message of "Wed, 16 Jan 2002 10:50:58 PST." <200201161850.g0GIowg68383@apollo.backplane.com>
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In message <200201161850.g0GIowg68383@apollo.backplane.com>, Matthew Dillon wri
tes:
> NFS fix). I think Ian's mknod tests are a no-brainer. They should
> just go in, as should my mknod fix.
I agree here - Matt's mknod fix and the S_IFMT mode bits corruption
bug that I fixed are simple fixes and they are both effectively
remotely exploitable (but only if you are running an NFS server,
and generally only by hosts listed in /etc/exports). The first bug
causes all processes to get stuck in state `inode', and the second
causes filesystem corruption that requires a manual fsck to fix.
Matt's mknod bug occurred during normal operation, but the other
probably only happens with a hostile client.
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/nfsserver/nfs_serv.c
mknod bug: revision 1.114
S_IFMT bug: revision 1.113
> #1 Fix corruption that can occur if a RW mount is downgraded to RO
> #2 Fix spl confusion that can occcur in ACQUIRE_LOCK*() softupdates
> routines
> #3 Fix softupdates panic that can occur during heavy I/O
> (see 'drain_output' calls in patch below)
>
> I have included Kirk's patch (for stable) below for review. It's a bit
> messy so I will note that the most important fix is #3 above, and it is
> a very simple and tiny portion of the below patch.
I'm not so sure about these. #3 looks simple on its own I suppose.
#1 has been around for years, and although annoying, the corruption
is simply that some blocks don't get freed until the next real fsck.
This fix was only committed to -current yesterday, and it has already
caused one problem there, so it's not looking too good from a gain
vs. risk POV :-) I'm not sure about #2 either; the patch isn't too
complex, but it's a bit strange.
http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/ufs/ffs/ffs_softdep.c
#2: 1.104
#3: 1.103
BTW is the VDRAINED stuff in your patch just left over from something
else? It doesn't seem to be present in -current.
Ian
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