> On Aug 20, 2020, at 3:39 PM, Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
>
> If an NFSv2/v3 client breaks an NFSv4 client's delegation, it will hit a
> NULL dereference in nfsd_breaker_owns_lease().
>
> Easily reproduceable with for example
>
> mount -overs=4.2 server:/export /mnt/
> sleep 1h </mnt/file &
> mount -overs=3 server:/export /mnt2/
> touch /mnt2/file
>
> Reported-by: Robert Dinse <nanook@xxxxxxxxxx>
> Fixes: 28df3d1539de50 ("nfsd: clients don't need to break their own delegations")
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
I think I've got this queued already. Is this different than:
http://git.linux-nfs.org/?p=cel/cel-2.6.git;a=commit;h=34b09af4f54e6485e28f138ccad159611a240cc1
> ---
> fs/nfsd/nfs4state.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> Oops, I've had this sitting around a couple weeks but I must have
> forgotten to send it in. This is needed for 5.9.
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 4b70657385f2..0e5302f6df52 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4598,6 +4598,8 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
> if (!i_am_nfsd())
> return NULL;
> rqst = kthread_data(current);
> + if (!rqst->rq_lease_breaker)
> + return NULL;
> clp = *(rqst->rq_lease_breaker);
> return dl->dl_stid.sc_client == clp;
> }
> --
> 2.26.2
>
--
Chuck Lever
