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    Subject[PATCH 3.12 092/133] vfs: Is mounted should be testing mnt_ns for NULL or error.
    Date
    3.12-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "Eric W. Biederman" <ebiederm@xmission.com>

    commit 260a459d2e39761fbd39803497205ce1690bc7b1 upstream.

    A bug was introduced with the is_mounted helper function in
    commit f7a99c5b7c8bd3d3f533c8b38274e33f3da9096e
    Author: Al Viro <viro@zeniv.linux.org.uk>
    Date: Sat Jun 9 00:59:08 2012 -0400

    get rid of ->mnt_longterm

    it's enough to set ->mnt_ns of internal vfsmounts to something
    distinct from all struct mnt_namespace out there; then we can
    just use the check for ->mnt_ns != NULL in the fast path of
    mntput_no_expire()

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

    The intent was to test if the real_mount(vfsmount)->mnt_ns was
    NULL_OR_ERR but the code is actually testing real_mount(vfsmount)
    and always returning true.

    The result is d_absolute_path returning paths it should be hiding.

    Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/mount.h | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/fs/mount.h
    +++ b/fs/mount.h
    @@ -73,7 +73,7 @@ static inline int mnt_has_parent(struct
    static inline int is_mounted(struct vfsmount *mnt)
    {
    /* neither detached nor internal? */
    - return !IS_ERR_OR_NULL(real_mount(mnt));
    + return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
    }

    extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);



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