On Fri, 2024-12-20 at 15:28 +1100, NeilBrown wrote:
> A recent patch inadvertently broke callbacks for NFSv4.0.
>
> In the 4.0 case we do not expect a session to be found but still need to
> call setup_callback_client() which will not try to dereference it.
>
> This patch moves the check for failure to find a session into the 4.1+
> branch of setup_callback_client()
>
> Fixes: 1e02c641c3a4 ("NFSD: Prevent NULL dereference in nfsd4_process_cb_update()")
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> fs/nfsd/nfs4callback.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 4ea99c47cd9d..e4a1d2d9b24a 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -1135,7 +1135,7 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
> args.authflavor = clp->cl_cred.cr_flavor;
> clp->cl_cb_ident = conn->cb_ident;
> } else {
> - if (!conn->cb_xprt)
> + if (!conn->cb_xprt || !ses)
> return -EINVAL;
> clp->cl_cb_session = ses;
> args.bc_xprt = conn->cb_xprt;
> @@ -1557,8 +1557,6 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
> ses = c->cn_session;
> }
> spin_unlock(&clp->cl_lock);
> - if (!c)
> - return;
>
> err = setup_callback_client(clp, &conn, ses);
> if (err) {
>
> base-commit: 8d5b7358ea7c07b69c44f0af21ebc79a49cf12a3
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
