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From:   Kees Cook <keescook@chromium.org>
Date:   Thu, 7 Jun 2018 12:29:26 -0700
Message-ID: <CAGXu5jJt_Y5KJwCKVPpTFOBt36aDAG9TqbB2bWAdu+2oGV5cZg@mail.gmail.com>
Subject: Re: [PATCH 1/6] Convert virtio_console to struct_size
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Matthew Wilcox <mawilcox@microsoft.com>,
        Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>
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On Thu, Jun 7, 2018 at 7:57 AM, Matthew Wilcox <willy@infradead.org> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
> ---
>  drivers/char/virtio_console.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 21085515814f..4bf7c06c2343 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -433,8 +433,7 @@ static struct port_buffer *alloc_buf(struct virtio_device *vdev, size_t buf_size
>          * Allocate buffer and the sg list. The sg list array is allocated
>          * directly after the port_buffer struct.
>          */
> -       buf = kmalloc(sizeof(*buf) + sizeof(struct scatterlist) * pages,
> -                     GFP_KERNEL);
> +       buf = kmalloc(struct_size(buf, sg, pages), GFP_KERNEL);
>         if (!buf)
>                 goto fail;

I feel like this one should have been caught by Coccinelle... maybe
the transitive case got missed? Regardless, I'll figure out how to
improve the script and/or take these.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security