Re: [PATCH] nfsd: fix an IS_ERR() vs NULL check

J. Bruce Fields
2019-01-04T15:03:46Z

On Fri, Jan 04, 2019 at 09:47:03AM +0300, Dan Carpenter wrote:
> The get_backchannel_cred() used to return error pointers on error but
> now it returns NULL pointers.

Thanks! Queueing up for 4.21 and stable.

Off the top of my head I don't recall bug reports that could be
explained by this. Perhaps it's hard to get a failure at this point
without failing somewhere earlier? But I think it's likely possible to
trigger a NULL dereference somehow.

--b.

>
> Fixes: 97f68c6b02e0 ("SUNRPC: add 'struct cred *' to auth_cred and rpc_cre")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> fs/nfsd/nfs4callback.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index c74e4538d0eb..9b38dab1c21b 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -913,9 +913,9 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
> return PTR_ERR(client);
> }
> cred = get_backchannel_cred(clp, client, ses);
> - if (IS_ERR(cred)) {
> + if (!cred) {
> rpc_shutdown_client(client);
> - return PTR_ERR(cred);
> + return -ENOMEM;
> }
> clp->cl_cb_client = client;
> clp->cl_cb_cred = cred;
> --
> 2.17.1