linux-kernel - [PATCH] locks: fix NULL-deref in generic_delete

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Message-ID: <20150113151743.7c260163@notabene.brown>
Date:	Tue, 13 Jan 2015 15:17:43 +1300
From:	NeilBrown <neilb@...e.de>
To:	Jeff Layton <jeff.layton@...marydata.com>,
	"L. A. Walsh" <suse@...nx.org>, linux-kernel@...r.kernel.org,
	linux-nfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc:	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH] locks: fix NULL-deref in generic_delete_lease



commit 0efaa7e82f02fe69c05ad28e905f31fc86e6f08e
  locks: generic_delete_lease doesn't need a file_lock at all

moves the call to fl->fl_lmops->lm_change() to a place in the
code where fl might be a non-lease lock.
When that happens, fl_lmops is NULL and an Oops ensures.

So add an extra test to restore correct functioning.

Reported-by: Linda Walsh <suse@...nx.org>
Link: https://bugzilla.suse.com/show_bug.cgi?id=912569
Cc: stable@...r.kernel.org (v3.18)
Fixes: 0efaa7e82f02fe69c05ad28e905f31fc86e6f08e
Signed-off-by: NeilBrown <neilb@...e.de>
---
 fs/locks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/locks.c b/fs/locks.c
index 735b8d3fa78c..59e2f905e4ff 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1702,7 +1702,7 @@ static int generic_delete_lease(struct file *filp)
 			break;
 	}
 	trace_generic_delete_lease(inode, fl);
-	if (fl)
+	if (fl && IS_LEASE(fl))
 		error = fl->fl_lmops->lm_change(before, F_UNLCK, &dispose);
 	spin_unlock(&inode->i_lock);
 	locks_dispose_list(&dispose);
-- 
2.1.1


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