From 93be5f3334394aa9a1794007aed79e75cf4d348b Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Mon, 21 Jun 2021 10:19:58 +0800 Subject: [PATCH] usb: limit combined packets to 1 MiB (CVE-2021-3527) Fix CVE-2021-3527 usb-host and usb-redirect try to batch bulk transfers by combining many small usb packets into a single, large transfer request, to reduce the overhead and improve performance. This patch adds a size limit of 1 MiB for those combined packets to restrict the host resources the guest can bind that way. Signed-off-by: Gerd Hoffmann's avatarGerd Hoffmann Message-Id: <20210503132915.2335822-6-kraxel@redhat.com> Signed-off-by: Jiajie Li --- hw/usb/combined-packet.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/hw/usb/combined-packet.c b/hw/usb/combined-packet.c index 5d57e883dc..e56802f89a 100644 --- a/hw/usb/combined-packet.c +++ b/hw/usb/combined-packet.c @@ -171,7 +171,9 @@ void usb_ep_combine_input_packets(USBEndpoint *ep) if ((p->iov.size % ep->max_packet_size) != 0 || !p->short_not_ok || next == NULL || /* Work around for Linux usbfs bulk splitting + migration */ - (totalsize == (16 * KiB - 36) && p->int_req)) { + (totalsize == (16 * KiB - 36) && p->int_req) || + /* Next package may grow combined package over 1MiB */ + totalsize > 1 * MiB - ep->max_packet_size) { usb_device_handle_data(ep->dev, first); assert(first->status == USB_RET_ASYNC); if (first->combined) { -- 2.27.0