linux-kernel - Re: [PATCH] fs: reiserfs: free new_opts in reiserfs

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Date:   Wed, 27 Oct 2021 18:19:00 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Yu Kuai <yukuai3@...wei.com>, Miklos Szeredi <mszeredi@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        David Howells <dhowells@...hat.com>,
        reiserfs-devel@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs: reiserfs: free new_opts in reiserfs_remount

On Wed, Oct 27, 2021 at 5:46 PM Jan Kara <jack@...e.cz> wrote:
>
> On Wed 27-10-21 11:39:25, Dongliang Mu wrote:
> > Since the commit c3d98ea08291 ("VFS: Don't use save/replace_mount_options
> > if not using generic_show_options") eliminates replace_mount_options
> > in reiserfs, but did not handle the allocated new_opts,
> > it will cause memory leak in the reiserfs_remount.
> >
> > Fix this by freeing new_opts in the reiserfs_remount temporarily.
> >
> > Fixes: c3d98ea08291 ("VFS: Don't use save/replace_mount_options if not using generic_show_options")
> > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
>
> Thanks for the patch but I can see that new_opts is not actually used at
> all in reiserfs_remount() so we should perhaps just remove them (including
> kstrdup() et al).

That's also a plan. Since I am not sure if maintainers will use
new_opts anymore, So I propose a temporary patch to fix this memory
leak.

If you think new_opts is not used anymore, let's remove all the code
related to new_opts.

>
>                                                                 Honza
>
> > ---
> >  fs/reiserfs/super.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
> > index 58481f8d63d5..b36865c8b66a 100644
> > --- a/fs/reiserfs/super.c
> > +++ b/fs/reiserfs/super.c
> > @@ -1594,6 +1594,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
> >       }
> >
> >  out_ok_unlocked:
> > +     kfree(new_opts);
> >       return 0;
> >
> >  out_err_unlock:
> > --
> > 2.25.1
> >
> --
> Jan Kara <jack@...e.com>
> SUSE Labs, CR