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@xxxxxxxxxxxxxxx
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@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
>
--
Chuck Lever
