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SubjectRe: [PATCH] spi: spidev: use memdup_user
On Sat, May 6, 2017 at 5:42 PM, Geliang Tang <geliangtang@gmail.com> wrote:
> Use memdup_user() helper instead of open-coding to simplify the code.
>
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

> --- a/drivers/spi/spidev.c
> +++ b/drivers/spi/spidev.c
> @@ -325,7 +325,6 @@ static struct spi_ioc_transfer *
> spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
> unsigned *n_ioc)
> {
> - struct spi_ioc_transfer *ioc;
> u32 tmp;
>
> /* Check type, command number and direction */
> @@ -342,14 +341,7 @@ spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
> return NULL;
>
> /* copy into scratch area */
> - ioc = kmalloc(tmp, GFP_KERNEL);
> - if (!ioc)
> - return ERR_PTR(-ENOMEM);
> - if (__copy_from_user(ioc, u_ioc, tmp)) {

Note that as memdup_user() calls copy_from_user(), it repeats the access_ok()
check already done by spidev_ioctl().

> - kfree(ioc);
> - return ERR_PTR(-EFAULT);
> - }
> - return ioc;
> + return memdup_user(u_ioc, tmp);

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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