From 0ee9608c89e81a1ccee52ecb58a7ff040e2522d9 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 5 Nov 2015 00:01:51 +0100 Subject: [PATCH] debugfs: fix refcount imbalance in start_creating 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") Cc: stable@vger.kernel.org # v4.0+ Signed-off-by: Daniel Borkmann Signed-off-by: Al Viro --- fs/debugfs/inode.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 5d8f35f1382a..b7fcc0de0b2f 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -271,8 +271,12 @@ static struct dentry *start_creating(const char *name, struct dentry *parent) 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; } -- 2.20.1