This is a note to let you know that I've just added the patch titled nfsd: restore callback functionality for NFSv4.0 to the 6.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfsd-restore-callback-functionality-for-nfsv4.0.patch and it can be found in the queue-6.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 655199878ea5dbc966311df355b0bbc942a8dd99 Author: NeilBrown <neilb@xxxxxxx> Date: Fri Dec 20 15:28:18 2024 +1100 nfsd: restore callback functionality for NFSv4.0 [ Upstream commit 7917f01a286ce01e9c085e24468421f596ee1a0c ] 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> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index b8cbb1556004..de0763652549 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -1058,7 +1058,7 @@ 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; @@ -1461,8 +1461,6 @@ 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) {