From 05a40b172e4d691371534828078be47e7fff524c Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Mon, 3 May 2021 15:29:15 +0200
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Subject: [PATCH] usb: limit combined packets to 1 MiB (CVE-2021-3527)
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usb-host and usb-redirect try to batch bulk transfers by combining many
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small usb packets into a single, large transfer request, to reduce the
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overhead and improve performance.
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This patch adds a size limit of 1 MiB for those combined packets to
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restrict the host resources the guest can bind that way.
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Message-Id: <20210503132915.2335822-6-kraxel@redhat.com>
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Upstream-Status: Backport
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https://gitlab.com/qemu-project/qemu/-/commit/05a40b172e4d691371534828078be47e7fff524c
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CVE: CVE-2021-3527
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Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
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---
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hw/usb/combined-packet.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/hw/usb/combined-packet.c b/hw/usb/combined-packet.c
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index 5d57e883dc..e56802f89a 100644
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--- a/hw/usb/combined-packet.c
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+++ b/hw/usb/combined-packet.c
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@@ -171,7 +171,9 @@ void usb_ep_combine_input_packets(USBEndpoint *ep)
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if ((p->iov.size % ep->max_packet_size) != 0 || !p->short_not_ok ||
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next == NULL ||
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/* Work around for Linux usbfs bulk splitting + migration */
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- (totalsize == (16 * KiB - 36) && p->int_req)) {
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+ (totalsize == (16 * KiB - 36) && p->int_req) ||
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+ /* Next package may grow combined package over 1MiB */
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+ totalsize > 1 * MiB - ep->max_packet_size) {
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usb_device_handle_data(ep->dev, first);
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assert(first->status == USB_RET_ASYNC);
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if (first->combined) {
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--
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GitLab
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