Message-ID: <63f01810.170a0220.110a8.6fe1@mx.google.com>
Date:   Fri, 17 Feb 2023 16:13:03 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Namjae Jeon <linkinjeon@kernel.org>
Cc:     Steve French <sfrench@samba.org>, Paulo Alcantara <pc@cjr.nz>,
        Ronnie Sahlberg <lsahlber@redhat.com>,
        Shyam Prasad N <sprasad@microsoft.com>,
        Tom Talpey <tom@talpey.com>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org,
        samba-technical@lists.samba.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] smb3: Replace smb2pdu 1-element arrays with
 flex-arrays
References: <20230214232928.gonna.714-kees@kernel.org>
 <CAKYAXd-fcukmXfdwiAxOxe+5c+Y6vvaoQ3ff-5sK+Zis0HgC5A@mail.gmail.com>
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On Thu, Feb 16, 2023 at 11:25:01PM +0900, Namjae Jeon wrote:
> Hi Kees,
> 
> >  /* Read flags */
> > @@ -730,7 +730,7 @@ struct smb2_read_rsp {
> >  	__le32 DataLength;
> >  	__le32 DataRemaining;
> >  	__le32 Flags;
> > -	__u8   Buffer[1];
> > +	__u8   Buffer[];
> >  } __packed;
> >
> 
> You seem to have missed -1 removal in the code below.

Ah; thanks for this heads-up. I will need a v3.

> ./fs/cifs/smb2ops.c:5632:       .read_rsp_size = sizeof(struct
> smb2_read_rsp) - 1,
> ./fs/cifs/smb2ops.c:5654:       .read_rsp_size = sizeof(struct
> smb2_read_rsp) - 1,
...

These are interesting -- they don't show up at all in the code. What I
mean is that they're data-only changes. I'll add that to my before/after
build sanity checks.

Thanks!

-Kees

-- 
Kees Cook