vhost: Check docket sk_family instead of call getname

commit 42d84c8490f9f0931786f1623191fcab397c3d64 upstream.

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: 3a4d5c94e9 ("vhost_net: a kernel-level virtio server")
Reported-by: syzbot+f2a62d07a5198c819c7b@syzkaller.appspotmail.com
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eugenio Pérez 2020-02-21 12:06:56 +01:00 committed by Greg Kroah-Hartman
parent c47655fba1
commit ad598a48fe

View File

@ -1187,10 +1187,6 @@ 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);
@ -1203,11 +1199,7 @@ 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;
}