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Message-ID: <CAJfpegtK=dh0yNdvxSC8YF6vOYqGPM5EOWny07jYDdFc0qfhTQ@mail.gmail.com>
Date: Mon, 24 Jul 2023 16:43:06 +0200
From: Miklos Szeredi <miklos@...redi.hu>
To: Andrea Righi <andrea.righi@...onical.com>
Cc: Amir Goldstein <amir73il@...il.com>, linux-unionfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/3] ovl: validate superblock in OVL_FS()
On Sun, 21 May 2023 at 10:28, Andrea Righi <andrea.righi@...onical.com> wrote:
>
> When CONFIG_OVERLAY_FS_DEBUG is enabled add an explicit check to make
> sure that OVL_FS() is always used with a valid overlayfs superblock.
> Otherwise trigger a WARN_ON_ONCE().
>
> Reviewed-by: Amir Goldstein <amir73il@...il.com>
> Signed-off-by: Andrea Righi <andrea.righi@...onical.com>
> ---
> fs/overlayfs/ovl_entry.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
> index b32c38fdf3c7..e156649d9c71 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -97,8 +97,20 @@ static inline struct mnt_idmap *ovl_upper_mnt_idmap(struct ovl_fs *ofs)
>
> extern struct file_system_type ovl_fs_type;
>
> +static inline bool is_ovl_fs_sb(struct super_block *sb)
> +{
> + return sb->s_type == &ovl_fs_type;
> +}
> +
> +#ifdef CONFIG_OVERLAY_FS_DEBUG
> +#define OVL_VALIDATE_SB(__sb) WARN_ON_ONCE(!is_ovl_fs_sb(__sb))
> +#else
> +#define OVL_VALIDATE_SB(__sb)
> +#endif
> +
> static inline struct ovl_fs *OVL_FS(struct super_block *sb)
> {
> + OVL_VALIDATE_SB(sb);
This could be written simply and naturally:
if (IS_ENABLED(CONFIG_OVERLAY_FS_DEBUG))
WARN_ON_ONCE(sb->s_type != &ovl_fs_type)
Thanks,
Miklos
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