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>
---
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
