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

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Message-ID: <CAH2r5mvjDAgB6-kE=AOAwrETVk+R79z6Gd8gMnOTWqG-6Mnybw@mail.gmail.com>
Date:   Sun, 17 Jan 2021 15:58:23 -0600
From:   Steve French <smfrench@...il.com>
To:     Aurélien Aptel <aaptel@...e.com>
Cc:     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.

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);

On Thu, Jan 14, 2021 at 3:26 AM Aurélien Aptel via samba-technical
<samba-technical@...ts.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,
> --
> Aurélien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
>
>


-- 
Thanks,

Steve