When multiple FREE_STATEIDs are sent for the same delegation stateid,
it can lead to a possible either use-after-tree or counter refcount
underflow errors.
In nfsd4_free_stateid() under the client lock we find a delegation
stateid, however the code drops the lock before calling nfs4_put_stid(),
that allows another FREE_STATE to find the stateid again. The first one
will proceed to then free the stateid which leads to either
use-after-free or decrementing already zerod counter.
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Olga Kornievskaia <okorniev@xxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ac1859c7cc9d..56b261608af4 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7154,6 +7154,7 @@ nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
switch (s->sc_type) {
case SC_TYPE_DELEG:
if (s->sc_status & SC_STATUS_REVOKED) {
+ s->sc_status |= SC_STATUS_CLOSED;
spin_unlock(&s->sc_lock);
dp = delegstateid(s);
list_del_init(&dp->dl_recall_lru);
--
2.43.5
