2020-08-05 19:12:24

by J. Bruce Fields

Subject: [PATCH] nfsd: fix oops on mixed NFSv4/NFSv3 client access

From: "J. Bruce Fields" <[email protected]>

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 <[email protected]>
Fixes: 28df3d1539de50 ("nfsd: clients don't need to break their own delegations")
Signed-off-by: J. Bruce Fields <[email protected]>
---
fs/nfsd/nfs4state.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9fc0a1b9e4dd..45f3832d70d4 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4597,6 +4597,8 @@ 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

2020-08-05 19:20:46

by Chuck Lever III

Subject: Re: [PATCH] nfsd: fix oops on mixed NFSv4/NFSv3 client access

Hi Bruce-

> On Aug 5, 2020, at 3:10 PM, [email protected] wrote:
>
> From: "J. Bruce Fields" <[email protected]>
>
> 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 <[email protected]>
> Fixes: 28df3d1539de50 ("nfsd: clients don't need to break their own delegations")

May I add

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208807

And send this in the first NFSD v5.9 -rc pull request?


> Signed-off-by: J. Bruce Fields <[email protected]>
> ---
> fs/nfsd/nfs4state.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 9fc0a1b9e4dd..45f3832d70d4 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4597,6 +4597,8 @@ 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

2020-08-05 20:06:39

by J. Bruce Fields

Subject: Re: [PATCH] nfsd: fix oops on mixed NFSv4/NFSv3 client access

On Wed, Aug 05, 2020 at 03:17:54PM -0400, Chuck Lever wrote:
> Hi Bruce-
>
> > On Aug 5, 2020, at 3:10 PM, [email protected] wrote:
> >
> > From: "J. Bruce Fields" <[email protected]>
> >
> > 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 <[email protected]>
> > Fixes: 28df3d1539de50 ("nfsd: clients don't need to break their own delegations")
>
> May I add
>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208807
>
> And send this in the first NFSD v5.9 -rc pull request?

Sounds good, thanks!

--b.

>
>
> > Signed-off-by: J. Bruce Fields <[email protected]>
> > ---
> > fs/nfsd/nfs4state.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 9fc0a1b9e4dd..45f3832d70d4 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -4597,6 +4597,8 @@ 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
>
>