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; }