Re: [PATCH 1/2] tun: Use memdup_user() rather than duplicating its implementation

Michael S. Tsirkin
2016-08-22T01:43:53Z

On Sat, Aug 20, 2016 at 09:34:56AM +0200, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sat, 20 Aug 2016 08:54:15 +0200
>
> Reuse existing functionality from memdup_user() instead of keeping
> duplicate source code.
>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
> drivers/net/tun.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 9c8b5bc..a1aeccb 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -731,14 +731,9 @@ static int update_filter(struct tap_filter *filter, void __user *arg)
> }
>
> alen = ETH_ALEN * uf.count;
> - addr = kmalloc(alen, GFP_KERNEL);
> - if (!addr)
> - return -ENOMEM;
> -
> - if (copy_from_user(addr, arg + sizeof(uf), alen)) {
> - err = -EFAULT;
> - goto done;
> - }
> + addr = memdup_user(arg + sizeof(uf), alen);
> + if (IS_ERR(addr))
> + return PTR_ERR(addr);
>
> /* The filter is updated without holding any locks. Which is
> * perfectly safe. We disable it first and in the worst
> --
> 2.9.3