From 2b0a54f7fb36836f148a3a237fd0ee99a1a300a2 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 18 Aug 2021 14:05:05 +0200
Subject: [PATCH] uas: add stream number sanity checks.
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The device uses the guest-supplied stream number unchecked, which can
lead to guest-triggered out-of-band access to the UASDevice->data3 and
UASDevice->status3 fields.  Add the missing checks.

Fixes: CVE-2021-3713
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reported-by: Chen Zhe <chenzhe@huawei.com>
Reported-by: Tan Jingguo <tanjingguo@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210818120505.1258262-2-kraxel@redhat.com>
---
 hw/usb/dev-uas.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/usb/dev-uas.c b/hw/usb/dev-uas.c
index abd8070d0c..82bbc0d083 100644
--- a/hw/usb/dev-uas.c
+++ b/hw/usb/dev-uas.c
@@ -827,6 +827,9 @@ static void usb_uas_handle_data(USBDevice *dev, USBPacket *p)
         }
         break;
     case UAS_PIPE_ID_STATUS:
+        if (p->stream > UAS_MAX_STREAMS) {
+            goto err_stream;
+        }
         if (p->stream) {
             QTAILQ_FOREACH(st, &uas->results, next) {
                 if (st->stream == p->stream) {
@@ -854,6 +857,9 @@ static void usb_uas_handle_data(USBDevice *dev, USBPacket *p)
         break;
     case UAS_PIPE_ID_DATA_IN:
     case UAS_PIPE_ID_DATA_OUT:
+        if (p->stream > UAS_MAX_STREAMS) {
+            goto err_stream;
+        }
         if (p->stream) {
             req = usb_uas_find_request(uas, p->stream);
         } else {
@@ -889,6 +895,11 @@ static void usb_uas_handle_data(USBDevice *dev, USBPacket *p)
         p->status = USB_RET_STALL;
         break;
     }
+
+err_stream:
+    error_report("%s: invalid stream %d", __func__, p->stream);
+    p->status = USB_RET_STALL;
+    return;
 }
 
 static void usb_uas_unrealize(USBDevice *dev, Error **errp)
-- 
2.27.0

