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SubjectRe: [PATCH v3] staging: gdm724x: Fix DMA from stack
On Wed, Feb 10, 2021 at 07:55:12PM +0530, Amey Narkhede wrote:
> Stack allocated buffers cannot be used for DMA
> on all architectures so allocate hci_packet buffer
> using kmalloc.
>
> Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> ---
> Changes in v3:
> - Remove superfluous buf pointer
> - Reduce size of allocation of hci_packet to match number of
> bytes used for DMA
>
> drivers/staging/gdm724x/gdm_usb.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/gdm724x/gdm_usb.c b/drivers/staging/gdm724x/gdm_usb.c
> index dc4da66c3..80c58a3ef 100644
> --- a/drivers/staging/gdm724x/gdm_usb.c
> +++ b/drivers/staging/gdm724x/gdm_usb.c
> @@ -56,20 +56,24 @@ static int gdm_usb_recv(void *priv_dev,
>
> static int request_mac_address(struct lte_udev *udev)
> {
> - u8 buf[16] = {0,};
> - struct hci_packet *hci = (struct hci_packet *)buf;
> + struct hci_packet *hci;
> struct usb_device *usbdev = udev->usbdev;
> int actual;
> int ret = -1;
>
> + hci = kmalloc(5, GFP_KERNEL);

Why "5" and not:
hci = kmalloc(sizeof(*hci), GFP_KERNEL);
?

thanks,

greg k-h

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