On Mon, 23 Mar 2015 11:36:14 -0400 "J. Bruce Fields" <bfields@xxxxxxxxxxxx> wrote: > On Mon, Mar 23, 2015 at 10:53:42AM -0400, Jeff Layton wrote: > > alloc_init_open_stateowner can return an already freed entry if there is > > a race to put openowners in the hashtable. > > Looks like alloc_init_lock_stateowner has the same bug, so I'll apply > something like this pending testing. > > I wonder if it's actually possible to hit this one? > > --b. > > commit bdff3084f09f > Author: J. Bruce Fields <bfields@xxxxxxxxxx> > Date: Mon Mar 23 11:02:30 2015 -0400 > > nfsd: return correct lockowner when there is a race on hash insert > > alloc_init_lock_stateowner can return an already freed entry if there is > a race to put openowners in the hashtable. > > Noticed by inspection after Jeff Layton fixed the same bug for open > owners. Depending on client behavior, this one may be trickier to > trigger in practice. > > Fixes: c58c6610ec24 "nfsd: Protect adding/removing lock owners using client_lock" > Cc: stable@xxxxxxxxxxxxxxx> > Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > Cc: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index d2f2c37dc2db..49ae6116992f 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -5062,7 +5062,7 @@ alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp, > } else > nfs4_free_lockowner(&lo->lo_owner); > spin_unlock(&clp->cl_lock); > - return lo; > + return ret; > } > > static void Maybe. Commit b4019c0e219 allows us to do parallel LOCK/LOCKU calls for the same owner, but it also says: "Note, however, that we still serialise on the open stateid if the lock stateid is unconfirmed." ...which I take to mean that the initial LOCK calls likely wouldn't race this way. Still, it's probably possible to craft a pynfs test or something that does that. Either way, it's clearly a bug that should be fixed: Acked-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
