linux-kernel - Re: Regression, bisected: sqlite locking failure on nfs

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Date:	Mon, 01 Nov 2010 16:35:29 -0400
From:	Trond Myklebust <Trond.Myklebust@...app.com>
To:	Chuck Lever <chuck.lever@...cle.com>
Cc:	Nick Bowler <nbowler@...iptictech.com>,
	LKML Kernel <linux-kernel@...r.kernel.org>,
	"J. Bruce Fields" <bfields@...hat.com>,
	Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: Regression, bisected: sqlite locking failure on nfs

On Mon, 2010-11-01 at 15:55 -0400, Chuck Lever wrote:
> On Nov 1, 2010, at 3:48 PM, Trond Myklebust wrote:
> 
> > On Mon, 2010-11-01 at 15:45 -0400, Chuck Lever wrote:
> >> On Nov 1, 2010, at 3:42 PM, Trond Myklebust wrote:
> >> 
> >>> On Mon, 2010-11-01 at 15:22 -0400, Trond Myklebust wrote:
> >>>> I suspect nlmclnt_lookup_host() is to blame. It appears to be the _only_
> >>>> thing in the kernel that actually sets this 'srcaddr' field, and it sets
> >>>> it to
> >>>> 
> >>>> const struct sockaddr source = {
> >>>> 	.sa_family      = AF_UNSPEC,
> >>>> };
> >>>> 
> >>>> You triggered the bug by removing the line
> >>>> 
> >>>> 	transport->srcaddr.ss_family = family;
> >>>> 
> >>>> from xs_create_sock().
> >>>> 
> >>>>  Trond
> >>> 
> >>> Does this fix the regression?
> >>> 
> >>> Trond
> >>> 
> >>> ----------------------------------------------------------------------------------------------
> >>> NLM: Fix a regression in lockd
> >>> 
> >>> From: Trond Myklebust <Trond.Myklebust@...app.com>
> >>> 
> >>> Nick Bowler reports:
> >>> There are no unusual messages on the client... but I just logged into
> >>> the server and I see lots of messages of the following form:
> >>> 
> >>> nfsd: request from insecure port (192.168.8.199:35766)!
> >>> nfsd: request from insecure port (192.168.8.199:35766)!
> >>> nfsd: request from insecure port (192.168.8.199:35766)!
> >>> nfsd: request from insecure port (192.168.8.199:35766)!
> >>> nfsd: request from insecure port (192.168.8.199:35766)!
> >>> 
> >>> Bisected to commit 9247685088398cf21bcb513bd2832b4cd42516c4 (SUNRPC:
> >>> Properly initialize sock_xprt.srcaddr in all cases)
> >>> 
> >>> Apparently, removing the 'transport->srcaddr.ss_family = family' from
> >>> xs_create_sock() triggers this due to nlmclnt_lookup_host() incorrectly
> >>> initialising the srcaddr family to AF_UNSPEC.
> >>> 
> >>> Reported-by: Nick Bowler <nbowler@...iptictech.com>
> >>> Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
> >>> ---
> >>> 
> >>> fs/lockd/host.c |    5 -----
> >>> 1 files changed, 0 insertions(+), 5 deletions(-)
> >>> 
> >>> 
> >>> diff --git a/fs/lockd/host.c b/fs/lockd/host.c
> >>> index 25e21e4..9ff0c0e 100644
> >>> --- a/fs/lockd/host.c
> >>> +++ b/fs/lockd/host.c
> >>> @@ -238,9 +238,6 @@ struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
> >>> 				     const char *hostname,
> >>> 				     int noresvport)
> >>> {
> >>> -	const struct sockaddr source = {
> >>> -		.sa_family	= AF_UNSPEC,
> >>> -	};
> >>> 	struct nlm_lookup_host_info ni = {
> >>> 		.server		= 0,
> >>> 		.sap		= sap,
> >>> @@ -249,8 +246,6 @@ struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
> >>> 		.version	= version,
> >>> 		.hostname	= hostname,
> >>> 		.hostname_len	= strlen(hostname),
> >>> -		.src_sap	= &source,
> >>> -		.src_len	= sizeof(source),
> >>> 		.noresvport	= noresvport,
> >>> 	};
> >>> 
> >>> 
> >> 
> >> 
> >> What about that memcpy() in nlm_lookup_host()?  With this patch, wouldn't it be copying garbage into the host's srcaddr field?
> >> 
> > 
> > It shouldn't. ni->src_len is now zero.
> 
> Yech.  All this still assumes that ANYADDR is all zeroes, and that the memory this is going into is already initialized to zeroes.  It's asking for trouble if we re-arrange all this someday.
> 
> I've got an untested one line patch that should fix this for any upper layer caller.  Posting now.
> 

No! Upper layer callers should simply not be setting .saddress. Pretty
much the only thing that _should_ be setting .saddress is the lockd
callback, and possibly the nfsv4 server callback.

Trond
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