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From:   Benjamin Coddington <bcodding@redhat.com>
To:     bfields@fieldses.org, chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH V2] lockd: Fix invalid lockowner cast after vfs_test_lock
Date:   Mon, 26 Jul 2021 09:33:28 -0400
Message-Id: <a060024e4cde48b224a7b4aecae7d20423ce506f.1627306204.git.bcodding@redhat.com>
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References: <f94e02c019495fea4495fbef7498f342d5848dac.1627217317.git.bcodding@redhat.com>
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V2: fix typos in patch header

8<-------------------------------------------------------

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>
---
 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