linux-kernel - Re: [PATCH v2] binderfs: rework superblock destruction

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Date:   Tue, 23 Aug 2022 12:57:36 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Todd Kjos <tkjos@...roid.com>, linux-kernel@...r.kernel.org,
        Al Viro <viro@...iv.linux.org.uk>,
        Arve Hjønnevåg <arve@...roid.com>,
        Martijn Coenen <maco@...roid.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Carlos Llamas <cmllamas@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Dongliang Mu <mudongliangabcd@...il.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: [PATCH v2] binderfs: rework superblock destruction

On Tue, Aug 23, 2022 at 12:45:26PM +0200, Greg Kroah-Hartman wrote:
> On Tue, Aug 23, 2022 at 11:53:39AM +0200, Christian Brauner wrote:
> > From: Al Viro <viro@...iv.linux.org.uk>
> > 
> > So far we relied on
> > .put_super = binderfs_put_super()
> > to destroy info we stashed in sb->s_fs_info. This gave us the required ordering
> > between ->evict_inode() and sb->s_fs_info destruction.
> > 
> > But the current implementation of binderfs_fill_super() has a memory leak in
> > the rare circumstance that d_make_root() fails because ->put_super() is only
> > called when sb->s_root is initialized. Fix this by removing ->put_super() and
> > simply do all that work in binderfs_kill_super().
> > 
> > Reported-by: Dongliang Mu <mudongliangabcd@...il.com>
> > Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> > Signed-off-by: Christian Brauner (Microsoft) <brauner@...nel.org>
> > ---
> >  drivers/android/binderfs.c | 30 +++++++++++++++++-------------
> >  1 file changed, 17 insertions(+), 13 deletions(-)
> 
> What changed from v1?

Ah, forgot to add:

/* v2 */
Christian Brauner (Microsoft) <brauner@...nel.org>:
- Call kill_litter_super() before sb->s_fs_info cleanup.