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    Subject[PATCH AUTOSEL 5.5 30/67] vhost: Check docket sk_family instead of call getname
    Date
    From: Eugenio Pérez <eperezma@redhat.com>

    [ Upstream commit 42d84c8490f9f0931786f1623191fcab397c3d64 ]

    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@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: Sasha Levin <sashal@kernel.org>
    ---
    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 e158159671fa2..18e205eeb9af7 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;
    }
    --
    2.20.1
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