linux-hardening - Re: [PATCH] cifs: Avoid field over-reading memcpy()

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Date:   Mon, 21 Jun 2021 21:40:16 -0500
From:   Steve French <smfrench@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Steve French <stfrench@...rosoft.com>,
        LKML <linux-kernel@...r.kernel.org>,
        CIFS <linux-cifs@...r.kernel.org>,
        samba-technical <samba-technical@...ts.samba.org>,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] cifs: Avoid field over-reading memcpy()

merged into cifs-2.6.git for-next

On Mon, Jun 21, 2021 at 4:45 PM Kees Cook <keescook@...omium.org> wrote:
>
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally reading across neighboring fields.
>
> Instead of using memcpy to read across multiple struct members, just
> perform per-member assignments as already done for other members.
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  fs/cifs/smb2pdu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 31784e3fa96f..962826dc3316 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -2892,7 +2892,10 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
>  #endif /* CIFS_DEBUG2 */
>
>         if (buf) {
> -               memcpy(buf, &rsp->CreationTime, 32);
> +               buf->CreationTime = rsp->CreationTime;
> +               buf->LastAccessTime = rsp->LastAccessTime;
> +               buf->LastWriteTime = rsp->LastWriteTime;
> +               buf->ChangeTime = rsp->ChangeTime;
>                 buf->AllocationSize = rsp->AllocationSize;
>                 buf->EndOfFile = rsp->EndofFile;
>                 buf->Attributes = rsp->FileAttributes;
> --
> 2.30.2
>


-- 
Thanks,

Steve