[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20230119135721.83345-3-alexander.shishkin@linux.intel.com>
Date: Thu, 19 Jan 2023 15:57:17 +0200
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: mst@...hat.com, jasowang@...hat.com
Cc: virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, elena.reshetova@...el.com,
kirill.shutemov@...ux.intel.com, Andi Kleen <ak@...ux.intel.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Amit Shah <amit@...nel.org>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v1 2/6] virtio console: Harden port adding
From: Andi Kleen <ak@...ux.intel.com>
The ADD_PORT operation reads and sanity checks the port id multiple
times from the untrusted host. This is not safe because a malicious
host could change it between reads.
Read the port id only once and cache it for subsequent uses.
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Amit Shah <amit@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/char/virtio_console.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index f4fd5fe7cd3a..6599c2956ba4 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1563,10 +1563,13 @@ static void handle_control_message(struct virtio_device *vdev,
struct port *port;
size_t name_size;
int err;
+ unsigned id;
cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
- port = find_port_by_id(portdev, virtio32_to_cpu(vdev, cpkt->id));
+ /* Make sure the host cannot change id under us */
+ id = virtio32_to_cpu(vdev, READ_ONCE(cpkt->id));
+ port = find_port_by_id(portdev, id);
if (!port &&
cpkt->event != cpu_to_virtio16(vdev, VIRTIO_CONSOLE_PORT_ADD)) {
/* No valid header at start of buffer. Drop it. */
@@ -1583,15 +1586,14 @@ static void handle_control_message(struct virtio_device *vdev,
send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
break;
}
- if (virtio32_to_cpu(vdev, cpkt->id) >=
- portdev->max_nr_ports) {
+ if (id >= portdev->max_nr_ports) {
dev_warn(&portdev->vdev->dev,
"Request for adding port with "
"out-of-bound id %u, max. supported id: %u\n",
cpkt->id, portdev->max_nr_ports - 1);
break;
}
- add_port(portdev, virtio32_to_cpu(vdev, cpkt->id));
+ add_port(portdev, id);
break;
case VIRTIO_CONSOLE_PORT_REMOVE:
unplug_port(port);
--
2.39.0
Powered by blists - more mailing lists