On 7/23/20 9:50 PM, Cong Wang wrote:
> Similar to tun_net_xmit(), we have to orphan the skb
> before queuing it, otherwise we may use the socket when
> purging the queue after it is freed by user-space.
Which socket ?
By not calling skb_orphan(skb), this skb should own a reference on skb->sk
preventing
skb->sk to disappear.
It seems that instead of skb_orphan() here, we could avoid calling
skb_set_owner_w() in the first place,
because this is confusing.
Also, there seems to be no limit on number of skbs that can be queued, this
looks rather dangerous.
diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index
0cb4adfc6641da0b1add7a8b40957fd23df1e075..9b180768dbfe9ea100ad008d92522e340f73101e
100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -661,7 +661,6 @@ static void qrtr_port_remove(struct qrtr_sock *ipc)
pkt->client.node = cpu_to_le32(ipc->us.sq_node);
pkt->client.port = cpu_to_le32(ipc->us.sq_port);
- skb_set_owner_w(skb, &ipc->sk);
qrtr_bcast_enqueue(NULL, skb, QRTR_TYPE_DEL_CLIENT, &ipc->us,
&to);
}
@@ -855,7 +854,6 @@ static int qrtr_bcast_enqueue(struct qrtr_node *node,
struct sk_buff *skb,
skbn = skb_clone(skb, GFP_KERNEL);
if (!skbn)
break;
- skb_set_owner_w(skbn, skb->sk);
qrtr_node_enqueue(node, skbn, type, from, to);
}
mutex_unlock(&qrtr_node_lock);
>
> Reported-and-tested-by: syzbot+6720d64f31c081c2f...@syzkaller.appspotmail.com
> Fixes: 28fb4e59a47d ("net: qrtr: Expose tunneling endpoint to user space")
> Cc: Bjorn Andersson <bjorn.anders...@linaro.org>
> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
> ---
> net/qrtr/tun.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c
> index 15ce9b642b25..54a565dcfef3 100644
> --- a/net/qrtr/tun.c
> +++ b/net/qrtr/tun.c
> @@ -20,6 +20,7 @@ static int qrtr_tun_send(struct qrtr_endpoint *ep, struct
> sk_buff *skb)
> {
> struct qrtr_tun *tun = container_of(ep, struct qrtr_tun, ep);
>
> + skb_orphan(skb);
> skb_queue_tail(&tun->queue, skb);
>
> /* wake up any blocking processes, waiting for new data */
>
