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vhost: Check docket sk_family instead of call getname

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[ 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>
This commit is contained in:
Eugenio Pérez 2020-03-05 17:30:05 +01:00 committed by Greg Kroah-Hartman
parent 5f64b16c47
commit 79152052fb
1 changed files with 2 additions and 11 deletions
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13
drivers/vhost/net.c
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@ -815,11 +815,7 @@ 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 uaddr_len = sizeof uaddr, r;
int r;
struct socket *sock = sockfd_lookup(fd, &r);
if (!sock)
@ -831,12 +827,7 @@ static struct socket *get_raw_socket(int fd)
goto err;
}
r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
&uaddr_len, 0);
if (r)
goto err;
if (uaddr.sa.sll_family != AF_PACKET) {
if (sock->sk->sk_family != AF_PACKET) {
r = -EPFNOSUPPORT;
goto err;
}