On Fri, Feb 21, 2020 at 12:06:56PM +0100, Eugenio Pérez wrote:
> Doing so, we save one call to get data we already have in the struct.
>
> Also, since there is no guarantee that getname use sockaddr_ll
> parameter beyond its size, we add a little bit of security here.
> It should do not do beyond MAX_ADDR_LEN, but syzbot found that
> ax25_getname writes more (72 bytes, the size of full_sockaddr_ax25,
> versus 20 + 32 bytes of sockaddr_ll + MAX_ADDR_LEN in syzbot repro).
>
> Fixes: 3a4d5c94e9593 ("vhost_net: a kernel-level virtio server")
> Reported-by: syzbot+f2a62d07a5198c819c7b@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Eugenio Pérez <eperezma@xxxxxxxxxx>
Thanks for debugging this!
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/vhost/net.c | 10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index e158159671fa..18e205eeb9af 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -1414,10 +1414,6 @@ static int vhost_net_release(struct inode *inode, struct file *f)
>
> static struct socket *get_raw_socket(int fd)
> {
> - struct {
> - struct sockaddr_ll sa;
> - char buf[MAX_ADDR_LEN];
> - } uaddr;
> int r;
> struct socket *sock = sockfd_lookup(fd, &r);
>
> @@ -1430,11 +1426,7 @@ static struct socket *get_raw_socket(int fd)
> goto err;
> }
>
> - r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa, 0);
> - if (r < 0)
> - goto err;
> -
> - if (uaddr.sa.sll_family != AF_PACKET) {
> + if (sock->sk->sk_family != AF_PACKET) {
> r = -EPFNOSUPPORT;
> goto err;
> }
> --
> 2.18.1
