linux-kernel - Re: [PATCH v2 2/3] USB: ehci-tegra: fix inefficient copy of unaligned buffers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAH6sp9PFE_kQn5hpXaGhn6d_WTtKZUbfS-DpDRfRCKbBj9S4fQ@mail.gmail.com>
Date:	Thu, 23 Apr 2015 16:31:51 +0200
From:	Frans Klaver <fransklaver@...il.com>
To:	Johan Hovold <johan@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	linux-tegra@...r.kernel.org
Subject: Re: [PATCH v2 2/3] USB: ehci-tegra: fix inefficient copy of unaligned buffers

On Thu, Apr 23, 2015 at 4:06 PM, Johan Hovold <johan@...nel.org> wrote:
> Make sure only to copy any actual data rather than the whole buffer,
> when releasing the temporary buffer used for unaligned non-isochronous
> transfers.
>
> Compile-tested only.
>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---
>  drivers/usb/host/ehci-tegra.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
> index ff9af29b4e9f..4031b372008e 100644
> --- a/drivers/usb/host/ehci-tegra.c
> +++ b/drivers/usb/host/ehci-tegra.c
> @@ -304,6 +304,7 @@ struct dma_aligned_buffer {
>  static void free_dma_aligned_buffer(struct urb *urb)
>  {
>         struct dma_aligned_buffer *temp;
> +       size_t length;
>
>         if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
>                 return;
> @@ -311,9 +312,14 @@ static void free_dma_aligned_buffer(struct urb *urb)
>         temp = container_of(urb->transfer_buffer,
>                 struct dma_aligned_buffer, data);
>
> -       if (usb_urb_dir_in(urb))
> -               memcpy(temp->old_xfer_buffer, temp->data,
> -                      urb->transfer_buffer_length);
> +       if (usb_urb_dir_in(urb)) {
> +               if (usb_pipeisoc(urb->pipe))
> +                       length = urb->transfer_buffer_length;
> +               else
> +                       length = urb->actual_length;
> +
> +               memcpy(temp->old_xfer_buffer, temp->data, length);
> +       }
>         urb->transfer_buffer = temp->old_xfer_buffer;
>         kfree(temp->kmalloc_ptr);

Out of curiosity: any reason not to declare that length variable
inside this new compound?

Thanks,
Frans
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/