Re: [PATCH net-next] tuntap: add sanity checks about msg_controllen in sendmsg

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在 2022/3/3 上午10:24, Harold Huang 写道:
In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to
tun_sendmsg. Although we donot use msg_controllen in this path, we should
check msg_controllen to make sure the caller pass a valid msg_ctl.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505

Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Harold Huang <baymaxhuang@xxxxxxxxx>


Acked-by: Jason Wang <jasowang@xxxxxxxxxx>


---
  drivers/net/tap.c   | 3 ++-
  drivers/net/tun.c   | 3 ++-
  drivers/vhost/net.c | 1 +
  3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 8e3a28ba6b28..ba2ef5437e16 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1198,7 +1198,8 @@ static int tap_sendmsg(struct socket *sock, struct msghdr *m,
  	struct xdp_buff *xdp;
  	int i;
- if (ctl && (ctl->type == TUN_MSG_PTR)) {
+	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
+	    ctl && ctl->type == TUN_MSG_PTR) {
  		for (i = 0; i < ctl->num; i++) {
  			xdp = &((struct xdp_buff *)ctl->ptr)[i];
  			tap_get_user_xdp(q, xdp);
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 969ea69fd29d..2a0d8a5d7aec 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2501,7 +2501,8 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
  	if (!tun)
  		return -EBADFD;
- if (ctl && (ctl->type == TUN_MSG_PTR)) {
+	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
+	    ctl && ctl->type == TUN_MSG_PTR) {
  		struct tun_page tpage;
  		int n = ctl->num;
  		int flush = 0, queued = 0;
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 28ef323882fb..792ab5f23647 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -473,6 +473,7 @@ static void vhost_tx_batch(struct vhost_net *net,
  		goto signal_used;
msghdr->msg_control = &ctl;
+	msghdr->msg_controllen = sizeof(ctl);
  	err = sock->ops->sendmsg(sock, msghdr, 0);
  	if (unlikely(err < 0)) {
  		vq_err(&nvq->vq, "Fail to batch sending packets\n");




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