ACK: [CVE-2018-8822][Artful][SRU][PATCH] staging: ncpfs: memory corruption in ncp_read_kernel()

[Colin Ian King]

On 23/04/18 09:45, Po-Hsu Lin wrote:
> From: Dan Carpenter <dan.carpenter at oracle.com>
> 
> CVE-2018-8822
> 
> If the server is malicious then *bytes_read could be larger than the
> size of the "target" buffer.  It would lead to memory corruption when we
> do the memcpy().
> 
> Reported-by: Dr Silvio Cesare of InfoSect <Silvio Cesare <silvio.cesare at gmail.com>
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
> Cc: stable <stable at vger.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (backported from commit 4c41aa24baa4ed338241d05494f2c595c885af8f)
> Signed-off-by: Po-Hsu Lin <po-hsu.lin at canonical.com>
> ---
>  fs/ncpfs/ncplib_kernel.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/ncpfs/ncplib_kernel.c b/fs/ncpfs/ncplib_kernel.c
> index 88dbbc9..f571570 100644
> --- a/fs/ncpfs/ncplib_kernel.c
> +++ b/fs/ncpfs/ncplib_kernel.c
> @@ -980,6 +980,10 @@ ncp_read_kernel(struct ncp_server *server, const char *file_id,
>  		goto out;
>  	}
>  	*bytes_read = ncp_reply_be16(server, 0);
> +	if (*bytes_read > to_read) {
> +		result = -EINVAL;
> +		goto out;
> +	}
>  	source = ncp_reply_data(server, 2 + (offset & 1));
>  
>  	memcpy(target, source, *bytes_read);
> 

Looks good to me.

Acked-by: Colin Ian King <colin.king at canonical.com>