From 93340afddfbc4085a5297fe635b65dd7f7f3ef05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bernhard=20=C3=9Cbelacker?= <bernhardu@mailbox.org>
Date: Mon, 17 Dec 2018 00:05:43 +0100
Subject: [PATCH] mustek_usb2: Avoid stack smashing.  Fixes #35

Use a properly sized variable in call to sanei_usb_{read,write}_bulk.

Debian-Bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=886777
Debian-Bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=907972
---
 backend/mustek_usb2_asic.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/backend/mustek_usb2_asic.c b/backend/mustek_usb2_asic.c
index b5f3b0a4..b31c7494 100644
--- a/backend/mustek_usb2_asic.c
+++ b/backend/mustek_usb2_asic.c
@@ -255,6 +255,7 @@ Mustek_DMARead (PAsic chip, unsigned int size, SANE_Byte * lpdata)
   STATUS status = STATUS_GOOD;
   unsigned int i, buf[1];
   unsigned int read_size;
+  size_t read_size_usb;
 
   DBG (DBG_ASIC, "Mustek_DMARead: Enter\n");
 
@@ -268,9 +269,11 @@ Mustek_DMARead (PAsic chip, unsigned int size, SANE_Byte * lpdata)
       SetRWSize (chip, 1, buf[0]);
       status = WriteIOControl (chip, 0x03, 0, 4, (SANE_Byte *) (buf));
 
+      read_size_usb = buf[0];
       status =
 	sanei_usb_read_bulk (chip->fd, lpdata + i * read_size,
-			     (size_t *) buf);
+                             &read_size_usb);
+      buf[0] = read_size_usb;
       if (status != STATUS_GOOD)
 	{
 	  DBG (DBG_ERR, "Mustek_DMARead: read error\n");
@@ -284,9 +287,11 @@ Mustek_DMARead (PAsic chip, unsigned int size, SANE_Byte * lpdata)
       SetRWSize (chip, 1, buf[0]);
       status = WriteIOControl (chip, 0x03, 0, 4, (SANE_Byte *) (buf));
 
+      read_size_usb = buf[0];
       status =
 	sanei_usb_read_bulk (chip->fd, lpdata + i * read_size,
-			     (size_t *) buf);
+                             &read_size_usb);
+      buf[0] = read_size_usb;
       if (status != STATUS_GOOD)
 	{
 	  DBG (DBG_ERR, "Mustek_DMARead: read error\n");
@@ -307,6 +312,7 @@ Mustek_DMAWrite (PAsic chip, unsigned int size, SANE_Byte * lpdata)
   unsigned int buf[1];
   unsigned int i;
   unsigned int write_size;
+  size_t write_size_usb;
 
   DBG (DBG_ASIC, "Mustek_DMAWrite: Enter:size=%d\n", size);
 
@@ -320,9 +326,11 @@ Mustek_DMAWrite (PAsic chip, unsigned int size, SANE_Byte * lpdata)
       SetRWSize (chip, 0, buf[0]);
       WriteIOControl (chip, 0x02, 0, 4, (SANE_Byte *) buf);
 
+      write_size_usb = buf[0];
       status =
 	sanei_usb_write_bulk (chip->fd, lpdata + i * write_size,
-			      (size_t *) buf);
+                              &write_size_usb);
+      buf[0] = write_size_usb;
       if (status != STATUS_GOOD)
 	{
 	  DBG (DBG_ERR, "Mustek_DMAWrite: write error\n");
@@ -337,9 +345,11 @@ Mustek_DMAWrite (PAsic chip, unsigned int size, SANE_Byte * lpdata)
       SetRWSize (chip, 0, buf[0]);
       WriteIOControl (chip, 0x02, 0, 4, (SANE_Byte *) buf);
 
+      write_size_usb = buf[0];
       status =
 	sanei_usb_write_bulk (chip->fd, lpdata + i * write_size,
-			      (size_t *) buf);
+                              &write_size_usb);
+      buf[0] = write_size_usb;
       if (status != STATUS_GOOD)
 	{
 	  DBG (DBG_ERR, "Mustek_DMAWrite: write error\n");
-- 
2.20.1