On Mon, 4 Feb 2019 10:59:43 +0100
Anisse Astier <aastier@xxxxxxxxxx> wrote:
> GCC 8.2 gives this warning:
>
> virtio/net.c: In function ‘virtio_net__tap_init’:
> virtio/net.c:336:47: error: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]
> strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ndev->tap_name));
> ^
> virtio/net.c:348:47: error: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]
> strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ndev->tap_name));
> ^
>
> Fix it by using sizeof of destination instead, even if they're the same
> size in this case.
>
> Signed-off-by: Anisse Astier <aastier@xxxxxxxxxx>
Technically using strncpy still leaves the last byte in jeopardy, but
in this case it's fine since the buffers are the same size. So:
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
Cheers,
Andre.
> ---
> virtio/net.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/virtio/net.c b/virtio/net.c
> index a05f4cd..35ff2e9 100644
> --- a/virtio/net.c
> +++ b/virtio/net.c
> @@ -331,7 +331,7 @@ static bool virtio_net__tap_init(struct net_dev *ndev)
> goto fail;
> } else if (!skipconf) {
> memset(&ifr, 0, sizeof(ifr));
> - strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ndev->tap_name));
> + strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ifr.ifr_name));
> sin.sin_addr.s_addr = inet_addr(params->host_ip);
> memcpy(&(ifr.ifr_addr), &sin, sizeof(ifr.ifr_addr));
> ifr.ifr_addr.sa_family = AF_INET;
> @@ -343,7 +343,7 @@ static bool virtio_net__tap_init(struct net_dev *ndev)
>
> if (!skipconf) {
> memset(&ifr, 0, sizeof(ifr));
> - strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ndev->tap_name));
> + strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ifr.ifr_name));
> ioctl(sock, SIOCGIFFLAGS, &ifr);
> ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
> if (ioctl(sock, SIOCSIFFLAGS, &ifr) < 0)
> @@ -372,7 +372,7 @@ static void virtio_net__tap_exit(struct net_dev *ndev)
> return;
>
> sock = socket(AF_INET, SOCK_STREAM, 0);
> - strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ndev->tap_name));
> + strncpy(ifr.ifr_name, ndev->tap_name, sizeof(ifr.ifr_name));
> ioctl(sock, SIOCGIFFLAGS, &ifr);
> ifr.ifr_flags &= ~(IFF_UP | IFF_RUNNING);
> if (ioctl(sock, SIOCGIFFLAGS, &ifr) < 0)
