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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@tlinx.org>
Link: https://bugzilla.suse.com/show_bug.cgi?id=912569
Cc: stable@vger.kernel.org (v3.18)
Fixes: 0efaa7e82f02fe69c05ad28e905f31fc86e6f08e
Signed-off-by: NeilBrown <neilb@suse.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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