linux-kernel - Re: [PATCH] fs/cifs: Replace one-element array with flexible-array member.

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Message-ID: <CAH2r5mtaf6Kmg2RAxawsV9o=VHyu9hosqa4fZw5QDHLH-tacfg@mail.gmail.com>
Date:   Sun, 17 Jan 2021 20:08:21 -0600
From:   Steve French <smfrench@...il.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Aurélien Aptel <aaptel@...e.com>,
        Jiapeng Zhong <abaci-bugfix@...ux.alibaba.com>,
        Steve French <sfrench@...ba.org>,
        CIFS <linux-cifs@...r.kernel.org>,
        samba-technical <samba-technical@...ts.samba.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs/cifs: Replace one-element array with flexible-array member.

On Sun, Jan 17, 2021 at 6:02 PM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> On Sun, Jan 17, 2021 at 03:58:23PM -0600, Steve French wrote:
> > Jiapeng,
> > Aurelien is correct, you should respin this patch and correct for
> > where it breaks the sizeof calculation.  For example your change:
> >
> > struct smb2_lock_rsp {
> > @@ -1434,7 +1434,7 @@ struct smb2_query_directory_req {
> >         __le16 FileNameOffset;
> >         __le16 FileNameLength;
> >         __le32 OutputBufferLength;
> > -       __u8   Buffer[1];
> > +       __u8   Buffer[];
> >  } __packed;
> >
> > would have the side effect of making the file name off by one:
> >
> > smb2pdu.c-4654- req->FileNameOffset =
> > smb2pdu.c:4655:         cpu_to_le16(sizeof(struct
> > smb2_query_directory_req) - 1);
>
> FWIW, that sizeof() - 1 should've been offsetof()...

agreed

-- 
Thanks,

Steve