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From:   Steve French <smfrench@gmail.com>
Date:   Sun, 17 Jan 2021 15:58:23 -0600
Message-ID: <CAH2r5mvjDAgB6-kE=AOAwrETVk+R79z6Gd8gMnOTWqG-6Mnybw@mail.gmail.com>
Subject: Re: [PATCH] fs/cifs: Replace one-element array with flexible-array member.
To:     =?UTF-8?Q?Aur=C3=A9lien_Aptel?= <aaptel@suse.com>
Cc:     Jiapeng Zhong <abaci-bugfix@linux.alibaba.com>,
        Steve French <sfrench@samba.org>,
        CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>
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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 =3D
smb2pdu.c:4655:         cpu_to_le16(sizeof(struct
smb2_query_directory_req) - 1);

On Thu, Jan 14, 2021 at 3:26 AM Aur=C3=A9lien Aptel via samba-technical
<samba-technical@lists.samba.org> wrote:
>
> Hi Jiapeng,
>
> This will change the size returned by sizeof(). Have you checked that
> this doesn't introduce off-by-one errors in all the sizeof() usage?
>
> Cheers,
> --
> Aur=C3=A9lien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg,=
 DE
> GF: Felix Imend=C3=B6rffer, Mary Higgins, Sri Rasiah HRB 247165 (AG M=C3=
=BCnchen)
>
>


--=20
Thanks,

Steve