On Sat, Oct 05, 2024 at 12:20:48PM -0400, Jeff Layton wrote:
> On Sat, 2024-10-05 at 10:53 -0400, Chuck Lever wrote:
> > 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.
> >
>
> I don't know. It looks like nfsd4_free_stateid always returned
> NFS4ERR_LOCKS_HELD on a delegation stateid until 3f29cc82a84c.
>
> > 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").
> >
> >
>
> Maybe this one?
>
> 3f29cc82a84c nfsd: split sc_status out of sc_type
>
> That particular bit of the code (and the SC_STATUS_CLOSED flag) was
> added in that patch, and I don't think you'd want to apply this patch
> to anything that didn't have it.
OK, if we believe that 3f29cc82 is where the misbehavior started,
then I can replace the "Cc: stable@" with "Fixes: 3f29cc82a84c".
> > > 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
> > >
> >
>
> --
> Jeff Layton <jlayton@xxxxxxxxxx>
--
Chuck Lever
