Possible issue with rpc.idmapd and NFSv4.

[J. Bruce Fields]

On Thu, Dec 13, 2007 at 12:05:18PM -0500, Nathan Patwardhan wrote:
> On Dec 12, 2007 8:06 PM, Nathan Patwardhan <noopy.org at gmail.com> wrote:
> > On Dec 12, 2007 7:45 PM, Nathan Patwardhan <noopy.org at gmail.com> wrote:
> > > > So you've determined that nfs4_gid_to_name is returning non-zero when
> > > > given 600 as the gid?  Then the bug is probably in libnfsidmap.
> >
> > b is correct.  The issue is in libnfsidmap.  I installed
> > libnfsidmap-0.20 on our dev box just for kicks and the group issue
> > seems to have gone away.
> 
> I looked into the issue a little bit more last night and this morning.
>  The problem seems specific to nss.c and appears to exist in
> libnfsidmap-0.12 through libnfsidmap-0.19 (or thereabouts).
> 
> Specifically, there's a syconf(_SC_GETGR_R_SIZE_MAX) call in nss.c
> that results in a buffer that's never resize if ERANGE.

That sounds exactly right.  Un, in fact, here's where that was found
before:

	http://linux-nfs.org/pipermail/nfsv4/2007-April/005924.html

but without the attached patch.  It might also be possible to pull the
same patch out of CVS.

> I've written a patch for libnfsidmap-0.12 against libnfsidmap-0.20
> that seems to correct this issue, but at this point maybe such a patch
> is useless since libnfsidmap-0.12 is rather out of date.

> Please advise.

We don't maintain separate branches for older versions, so it's up to
the distributor to either apply this patch or upgrade to 0.20.

--b.