From 3f252a73e81aa01660cb426735eab932e6182e8d Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Fri, 15 Aug 2025 16:27:45 -0400 Subject: [PATCH] nfsd: handle get_client_locked() failure in nfsd4_setclientid_confirm() [ Upstream commit 908e4ead7f757504d8b345452730636e298cbf68 ] Lei Lu recently reported that nfsd4_setclientid_confirm() did not check the return value from get_client_locked(). a SETCLIENTID_CONFIRM could race with a confirmed client expiring and fail to get a reference. That could later lead to a UAF. Fix this by getting a reference early in the case where there is an extant confirmed client. If that fails then treat it as if there were no confirmed client found at all. In the case where the unconfirmed client is expiring, just fail and return the result from get_client_locked(). Reported-by: lei lu Closes: https://lore.kernel.org/linux-nfs/CAEBF3_b=UvqzNKdnfD_52L05Mqrqui9vZ2eFamgAbV0WG+FNWQ@mail.gmail.com/ Fixes: d20c11d86d8f ("nfsd: Protect session creation and client confirm using client_lock") Cc: stable@vger.kernel.org Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4state.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 1fd81ccf0c71..933de78918e3 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -3956,10 +3956,16 @@ nfsd4_setclientid_confirm(struct svc_rqst *rqstp, } status = nfs_ok; if (conf) { /* case 1: callback update */ - old = unconf; - unhash_client_locked(old); - nfsd4_change_callback(conf, &unconf->cl_cb_conn); - } else { /* case 3: normal case; new or rebooted client */ + if (get_client_locked(conf) == nfs_ok) { + old = unconf; + unhash_client_locked(old); + nfsd4_change_callback(conf, &unconf->cl_cb_conn); + } else { + conf = NULL; + } + } + + if (!conf) { /* case 3: normal case; new or rebooted client */ old = find_confirmed_client_by_name(&unconf->cl_name, nn); if (old) { status = nfserr_clid_inuse; @@ -3975,10 +3981,14 @@ nfsd4_setclientid_confirm(struct svc_rqst *rqstp, goto out; } } + status = get_client_locked(unconf); + if (status != nfs_ok) { + old = NULL; + goto out; + } move_to_confirmed(unconf); conf = unconf; } - get_client_locked(conf); spin_unlock(&nn->client_lock); nfsd4_probe_callback(conf); spin_lock(&nn->client_lock);