On Wed, Sep 17, 2014 at 10:50 AM, Steve Dickson <steved@xxxxxxxxxx> wrote:
> There is a race between nfs4_state_manager() and
> nfs_server_remove_lists() that happens during a nfsv3 mount.
>
> The v3 mount notices there is already a supper block so
> nfs_server_remove_lists() called which uses the nfs_client_lock
> spin lock to synchronize access to the client list.
>
> At the same time nfs4_state_manager() is running through
> the client list looking for work to do, using the same
> lock. When nfs4_state_manager() wins the race to the
> list, a v3 client pointer is found and not ignored
> properly which causes the panic.
>
> Moving some protocol checks before the state checking
> avoids the panic.
>
> CC: Stable Tree <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
> ---
> fs/nfs/nfs4client.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
> index 53e435a..7ff4c02 100644
> --- a/fs/nfs/nfs4client.c
> +++ b/fs/nfs/nfs4client.c
> @@ -622,6 +622,16 @@ int nfs41_walk_client_list(struct nfs_client *new,
>
> spin_lock(&nn->nfs_client_lock);
> list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
> +
> + if (pos->rpc_ops != new->rpc_ops)
> + continue;
> +
> + if (pos->cl_proto != new->cl_proto)
> + continue;
> +
> + if (pos->cl_minorversion != new->cl_minorversion)
> + continue;
> +
> /* If "pos" isn't marked ready, we can't trust the
> * remaining fields in "pos", especially the client
> * ID and serverowner fields. Wait for CREATE_SESSION
> @@ -647,15 +657,6 @@ int nfs41_walk_client_list(struct nfs_client *new,
> if (pos->cl_cons_state != NFS_CS_READY)
> continue;
>
> - if (pos->rpc_ops != new->rpc_ops)
> - continue;
> -
> - if (pos->cl_proto != new->cl_proto)
> - continue;
> -
> - if (pos->cl_minorversion != new->cl_minorversion)
> - continue;
> -
> if (!nfs4_match_clientids(pos, new))
> continue;
>
> --
> 1.8.3.1
>
Don't we need the same fix in nfs40_walk_client_list?
Cheers
Trond
--
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@xxxxxxxxxxxxxxx
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