| Re: [PATCH] [RFC] nfsd: fix possible dereference of static NULL nfsd_serv pointer [message #47104 is a reply to message #47101] |
Fri, 06 July 2012 17:26   |
bfields
Messages: 107
Registered: September 2007
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Senior Member |
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On Fri, Jul 06, 2012 at 05:45:56PM +0400, Stanislav Kinsbursky wrote:
> This is a bug fix for 3.5 kernel.
> In case on NFSd service start failure svc_shutdown_net() will call svc_destroy
> callback and zeroize global nfsd_serv pointer, this in turn will lead to Oops
> in svc_destroy().
>
> This patch is marked as RFC, because to many lines were changed. It can be
> easely simplified if requested.
> Moreover, NFSd service shutdown is going to be converted into csomething on
> per-net basis.
Doesn't this leave error paths in e.g. __write_ports_addfd() and
__write_ports_addxprt() unfixed?
I'm inclined to just submit your original fix (split up as in the last
version I sent) for 3.5 if you don't object.
--b.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> ---
> fs/nfsd/nfssvc.c | 14 ++++++++------
> 1 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index ee709fc..526a4aa 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -446,6 +446,7 @@ nfsd_svc(unsigned short port, int nrservs)
> int error;
> bool nfsd_up_before;
> struct net *net = &init_net;
> + struct svc_serv *serv = nfsd_serv;
>
> mutex_lock(&nfsd_mutex);
> dprintk("nfsd: creating service\n");
> @@ -454,7 +455,7 @@ nfsd_svc(unsigned short port, int nrservs)
> if (nrservs > NFSD_MAXSERVS)
> nrservs = NFSD_MAXSERVS;
> error = 0;
> - if (nrservs == 0 && nfsd_serv == NULL)
> + if (nrservs == 0 && serv == NULL)
> goto out;
>
> error = nfsd_create_serv();
> @@ -464,23 +465,24 @@ nfsd_svc(unsigned short port, int nrservs)
> nfsd_up_before = nfsd_up;
>
> error = nfsd_startup(port, nrservs);
> + error = -EINVAL;
> if (error)
> goto out_destroy;
> - error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
> + error = svc_set_num_threads(serv, NULL, nrservs);
> if (error)
> goto out_shutdown;
> /* We are holding a reference to nfsd_serv which
> * we don't want to count in the return value,
> * so subtract 1
> */
> - error = nfsd_serv->sv_nrthreads - 1;
> + error = serv->sv_nrthreads - 1;
> out_shutdown:
> if (error < 0 && !nfsd_up_before)
> nfsd_shutdown();
> out_destroy:
> - if (nfsd_serv->sv_nrthreads == 1)
> - svc_shutdown_net(nfsd_serv, net);
> - svc_destroy(nfsd_serv); /* Release server */
> + if (serv->sv_nrthreads == 1)
> + svc_shutdown_net(serv, net);
> + svc_destroy(serv); /* Release server */
> out:
> mutex_unlock(&nfsd_mutex);
> return error;
>
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