[PATCH 5.13 198/300] lockd: Fix invalid lockowner cast after vfs_test_lock

Greg Kroah-Hartman
2021-09-13T14:15:25Z

From: Benjamin Coddington <bcodding@redhat.com>

[ Upstream commit cd2d644ddba183ec7b451b7c20d5c7cc06fcf0d7 ]

After calling vfs_test_lock() the pointer to a conflicting lock can be
returned, and that lock is not guarunteed to be owned by nlm. In that
case, we cannot cast it to struct nlm_lockowner. Instead return the pid
of that conflicting lock.

Fixes: 646d73e91b42 ("lockd: Show pid of lockd for remote locks")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/lockd/svclock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 61d3cc2283dc..498cb70c2c0d 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -634,7 +634,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
conflock->caller = "somehost"; /* FIXME */
conflock->len = strlen(conflock->caller);
conflock->oh.len = 0; /* don't return OH info */
- conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
+ conflock->svid = lock->fl.fl_pid;
conflock->fl.fl_type = lock->fl.fl_type;
conflock->fl.fl_start = lock->fl.fl_start;
conflock->fl.fl_end = lock->fl.fl_end;
--
2.30.2