| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.8 085/255] nfsd: fix oops on mixed NFSv4/NFSv3 client access | Date | Tue, 1 Sep 2020 17:09:01 +0200 |
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From: J. Bruce Fields <bfields@redhat.com>
[ Upstream commit 34b09af4f54e6485e28f138ccad159611a240cc1 ]
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@eskimo.com> Fixes: 28df3d1539de50 ("nfsd: clients don't need to break their own delegations") BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208807 Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/nfsd/nfs4state.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index c9056316a0b35..cea682ce8aa12 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; } -- 2.25.1
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