hw-usb-core-fix-buffer-overflow

From 18ad0451f113ffc3a2ff59c059d189cca1e42842 Mon Sep 17 00:00:00 2001
From: root <root@localhost.localdomain>
Date: Wed, 19 Aug 2020 17:04:04 +0800
Subject: [PATCH] hw/usb/core.c fix buffer overflow

Store calculated setup_len in a local variable, verify it,
 and only write it to the struct (USBDevice->setup_len) in case it passed the
 sanity checks.

This prevents other code (do_token_{in,out} function specifically)
from working with invalid USBDevice->setup_len values and overruning
the USBDevice->setup_buf[] buffer.
Store
Fixes: CVE-2020-14364
Signed-off-by: Gred Hoffman <kraxel@redhat.com>
---
 hw/usb/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/usb/core.c b/hw/usb/core.c
index 5abd128b..12342f13 100644
--- a/hw/usb/core.c
+++ b/hw/usb/core.c
@@ -144,6 +144,8 @@ static void do_token_setup(USBDevice *s, USBPacket *p)
                 "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                 s->setup_len, sizeof(s->data_buf));
         p->status = USB_RET_STALL;
+		s->setup_len = 0;
+		s->setup_state = SETUP_STATE_ACK;
         return;
     }
 
@@ -277,6 +279,8 @@ static void do_parameter(USBDevice *s, USBPacket *p)
                 "usb_generic_handle_packet: ctrl buffer too small (%d > %zu)\n",
                 s->setup_len, sizeof(s->data_buf));
         p->status = USB_RET_STALL;
+		s->setup_len = 0;
+		s->setup_state = SETUP_STATE_ACK;
         return;
     }
 
-- 
2.23.0