This is a note to let you know that I've just added the patch titled
vhost_net: fix OoB on sendmsg() failure.
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vhost_net-fix-oob-on-sendmsg-failure.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ea355c13100be3c49d0ab0c590c0ca01f3970a4e
Author: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Wed Sep 8 13:42:09 2021 +0200
vhost_net: fix OoB on sendmsg() failure.
[ Upstream commit 3c4cea8fa7f71f00c5279547043a84bc2a4d8b8c ]
If the sendmsg() call in vhost_tx_batch() fails, both the 'batched_xdp'
and 'done_idx' indexes are left unchanged. If such failure happens
when batched_xdp == VHOST_NET_BATCH, the next call to
vhost_net_build_xdp() will access and write memory outside the xdp
buffers area.
Since sendmsg() can only error with EBADFD, this change addresses the
issue explicitly freeing the XDP buffers batch on error.
Fixes: 0a0be13b8fe2 ("vhost_net: batch submitting XDP buffers to underlayer sockets")
Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 48e574ae6033..cec9173aac6f 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -466,7 +466,7 @@ static void vhost_tx_batch(struct vhost_net *net,
.num = nvq->batched_xdp,
.ptr = nvq->xdp,
};
- int err;
+ int i, err;
if (nvq->batched_xdp == 0)
goto signal_used;
@@ -475,6 +475,15 @@ static void vhost_tx_batch(struct vhost_net *net,
err = sock->ops->sendmsg(sock, msghdr, 0);
if (unlikely(err < 0)) {
vq_err(&nvq->vq, "Fail to batch sending packets\n");
+
+ /* free pages owned by XDP; since this is an unlikely error path,
+ * keep it simple and avoid more complex bulk update for the
+ * used pages
+ */
+ for (i = 0; i < nvq->batched_xdp; ++i)
+ put_page(virt_to_head_page(nvq->xdp[i].data));
+ nvq->batched_xdp = 0;
+ nvq->done_idx = 0;
return;
}
