linux-kernel - RE: [PATCH] SUNRPC: Increase size of servername string

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Message-ID: <a717757cb2cb4f32afad046ce2f45117@AcuMS.aculab.com>
Date:   Fri, 25 Mar 2022 07:03:56 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     David Laight <David.Laight@...LAB.COM>,
        'NeilBrown' <neilb@...e.de>, Haowen Bai <baihaowen@...zu.com>
CC:     "trond.myklebust@...merspace.com" <trond.myklebust@...merspace.com>,
        "anna@...nel.org" <anna@...nel.org>,
        "chuck.lever@...cle.com" <chuck.lever@...cle.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Haowen Bai <baihaowen@...zu.com>
Subject: RE: [PATCH] SUNRPC: Increase size of servername string

From: David Laight
> Sent: 25 March 2022 06:53
> 
> From: NeilBrown
> > Sent: 25 March 2022 02:07
> >
> > On Thu, 24 Mar 2022, Haowen Bai wrote:
> > > This patch will fix the warning from smatch:
> > >
> > > net/sunrpc/clnt.c:562 rpc_create() error: snprintf() chops off
> > > the last chars of 'sun->sun_path': 108 vs 48
> > >
> > > Signed-off-by: Haowen Bai <baihaowen@...zu.com>
> > > ---
> > >  net/sunrpc/clnt.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> > > index c83fe61..6e0209e 100644
> > > --- a/net/sunrpc/clnt.c
> > > +++ b/net/sunrpc/clnt.c
> > > @@ -526,7 +526,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
> > >  		.servername = args->servername,
> > >  		.bc_xprt = args->bc_xprt,
> > >  	};
> > > -	char servername[48];
> > > +	char servername[108];
> >
> > It would be much nicer to use UNIX_PATH_MAX
> 
> Not on-stack....

Ok I looked the constant up - it is 108.
OTOH just looking at the code makes it look like a value
that is much larger - not good on stack.
Even [sizeof sun->sun_path] would probably be better.
But I don't think the copy is needed at all.

	David

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