This is a note to let you know that I've just added the patch titled vhost/vsock: fix incorrect used length reported to the guest to the 4.9-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-vsock-fix-incorrect-used-length-reported-to-the-guest.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 49d8c5ffad07ca014cfae72a1b9b8c52b6ad9cb8 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella <sgarzare@xxxxxxxxxx> Date: Mon, 22 Nov 2021 17:35:24 +0100 Subject: vhost/vsock: fix incorrect used length reported to the guest From: Stefano Garzarella <sgarzare@xxxxxxxxxx> commit 49d8c5ffad07ca014cfae72a1b9b8c52b6ad9cb8 upstream. The "used length" reported by calling vhost_add_used() must be the number of bytes written by the device (using "in" buffers). In vhost_vsock_handle_tx_kick() the device only reads the guest buffers (they are all "out" buffers), without writing anything, so we must pass 0 as "used length" to comply virtio spec. Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Cc: stable@xxxxxxxxxxxxxxx Reported-by: Halil Pasic <pasic@xxxxxxxxxxxxx> Suggested-by: Jason Wang <jasowang@xxxxxxxxxx> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> Link: https://lore.kernel.org/r/20211122163525.294024-2-sgarzare@xxxxxxxxxx Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/vhost/vsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -406,7 +406,7 @@ static void vhost_vsock_handle_tx_kick(s else virtio_transport_free_pkt(pkt); - vhost_add_used(vq, head, sizeof(pkt->hdr) + len); + vhost_add_used(vq, head, 0); added = true; } Patches currently in stable-queue which might be from sgarzare@xxxxxxxxxx are queue-4.9/vhost-vsock-fix-incorrect-used-length-reported-to-the-guest.patch