On Fri, Oct 04, 2024 at 06:04:03PM -0400, Olga Kornievskaia wrote:
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@vger.kernel.org
I assume that the broken commit is pretty old, but this fix does not apply before v6.9 (where sc_status is introduced). I can add "# v6.9+" to the Cc: stable tag.
But what do folks think about a Fixes: tag?
Could be e1ca12dfb1be ("NFSD: added FREE_STATEID operation"), but that doesn't have the switch statement, which was added by 2da1cec713bc ("nfsd4: simplify free_stateid").
Signed-off-by: Olga Kornievskaia okorniev@redhat.com
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