Re: [ 09/76] lockd: use rpc clients cl_nodename for id encoding

Ben Hutchings
2012-10-19T22:10:42Z

On Thu, Oct 18, 2012 at 07:46:33PM -0700, Greg Kroah-Hartman wrote:
> 3.6-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Stanislav Kinsbursky <skinsbursky@parallels.com>
>
> commit 303a7ce92064c285a04c870f2dc0192fdb2968cb upstream.
>
> Taking hostname from uts namespace if not safe, because this cuold be
> performind during umount operation on child reaper death. And in this case
> current->nsproxy is NULL already.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> fs/lockd/mon.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> --- a/fs/lockd/mon.c
> +++ b/fs/lockd/mon.c
> @@ -42,6 +42,7 @@ struct nsm_args {
> u32 proc;
>
> char *mon_name;
> + char *nodename;
> };
>
> struct nsm_res {
> @@ -141,6 +142,7 @@ static int nsm_mon_unmon(struct nsm_hand
> .vers = 3,
> .proc = NLMPROC_NSM_NOTIFY,
> .mon_name = nsm->sm_mon_name,
> + .nodename = utsname()->nodename,

Can we be sure that this string pointer will remain valid at the point
where current->nsproxy has become NULL? Or should nsm_args::nodename
actually be a copy of the string?

Ben.

> };
> struct rpc_message msg = {
> .rpc_argp = &args,
> @@ -477,7 +479,7 @@ static void encode_my_id(struct xdr_stre
> {
> __be32 *p;
>
> - encode_nsm_string(xdr, utsname()->nodename);
> + encode_nsm_string(xdr, argp->nodename);
> p = xdr_reserve_space(xdr, 4 + 4 + 4);
> *p++ = cpu_to_be32(argp->prog);
> *p++ = cpu_to_be32(argp->vers);

--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
- Albert Camus