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Date: Sat, 12 Dec 2015 11:33:35 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>,
Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 4.1 40/45] debugfs: fix refcount imbalance in start_creating
4.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Borkmann <daniel@...earbox.net>
commit 0ee9608c89e81a1ccee52ecb58a7ff040e2522d9 upstream.
In debugfs' start_creating(), we pin the file system to safely access
its root. When we failed to create a file, we unpin the file system via
failed_creating() to release the mount count and eventually the reference
of the vfsmount.
However, when we run into an error during lookup_one_len() when still
in start_creating(), we only release the parent's mutex but not so the
reference on the mount. Looks like it was done in the past, but after
splitting portions of __create_file() into start_creating() and
end_creating() via 190afd81e4a5 ("debugfs: split the beginning and the
end of __create_file() off"), this seemed missed. Noticed during code
review.
Fixes: 190afd81e4a5 ("debugfs: split the beginning and the end of __create_file() off")
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/debugfs/inode.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -276,8 +276,12 @@ static struct dentry *start_creating(con
dput(dentry);
dentry = ERR_PTR(-EEXIST);
}
- if (IS_ERR(dentry))
+
+ if (IS_ERR(dentry)) {
mutex_unlock(&d_inode(parent)->i_mutex);
+ simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+ }
+
return dentry;
}
--
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