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From d43b55595f9f5a29ad45b6bf1c899646ef623bf9 Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Fri, 4 Sep 2020 16:09:12 -0400
Subject: [PATCH 2/3] usb: check RNDIS message length

RH-Author: Jon Maloy <jmaloy@redhat.com>
Message-id: <20200904160913.87759-2-jmaloy@redhat.com>
Patchwork-id: 98289
O-Subject: [RHEL-7.9 qemu-kvm PATCH 1/2] usb: check RNDIS message length
Bugzilla: 1869693
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>

From: Prasad J Pandit <pjp@fedoraproject.org>

When processing remote NDIS control message packets, the USB Net
device emulator uses a fixed length(4096) data buffer. The incoming
packet length could exceed this limit. Add a check to avoid it.

Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1455648821-17340-2-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 64c9bc181fc78275596649f591302d72df2d3071)
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Jon Maloy <jmaloy.redhat.com>
---
 hw/usb/core.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/hw/usb/core.c b/hw/usb/core.c
index cf34755bba..f0201e30b4 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -128,9 +128,16 @@ static void do_token_setup(USBDevice *s, USBPacket *p)
     }
 
     usb_packet_copy(p, s->setup_buf, p->iov.size);
+    s->setup_index = 0;
     p->actual_length = 0;
     s->setup_len   = (s->setup_buf[7] << 8) | s->setup_buf[6];
-    s->setup_index = 0;
+    if (s->setup_len > sizeof(s->data_buf)) {
+        fprintf(stderr,
+                "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
+                s->setup_len, sizeof(s->data_buf));
+        p->status = USB_RET_STALL;
+        return;
+    }
 
     request = (s->setup_buf[0] << 8) | s->setup_buf[1];
     value   = (s->setup_buf[3] << 8) | s->setup_buf[2];
@@ -151,13 +158,6 @@ static void do_token_setup(USBDevice *s, USBPacket *p)
         }
         s->setup_state = SETUP_STATE_DATA;
     } else {
-        if (s->setup_len > sizeof(s->data_buf)) {
-            fprintf(stderr,
-                "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
-                s->setup_len, sizeof(s->data_buf));
-            p->status = USB_RET_STALL;
-            return;
-        }
         if (s->setup_len == 0)
             s->setup_state = SETUP_STATE_ACK;
         else
@@ -176,7 +176,7 @@ static void do_token_in(USBDevice *s, USBPacket *p)
     request = (s->setup_buf[0] << 8) | s->setup_buf[1];
     value   = (s->setup_buf[3] << 8) | s->setup_buf[2];
     index   = (s->setup_buf[5] << 8) | s->setup_buf[4];
- 
+
     switch(s->setup_state) {
     case SETUP_STATE_ACK:
         if (!(s->setup_buf[0] & USB_DIR_IN)) {
-- 
2.18.2