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vhost: Check docket sk_family instead of call getname

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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
1 changed files with 1 additions and 9 deletions

10
drivers/vhost/net.c
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;
}