From: Li Qiang <liqiang6-s@360.cn>
Date: Wed, 1 Feb 2017 08:35:01 +0000 (+0100)
Subject: cirrus: fix oob access issue (CVE-2017-2615)
X-Git-Tag: v2.8.1~52
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f054cead44cef75d330cfba39aa0c46be483813d;p=thirdparty%2Fqemu.git

cirrus: fix oob access issue (CVE-2017-2615)

When doing bitblt copy in backward mode, we should minus the
blt width first just like the adding in the forward mode. This
can avoid the oob access of the front of vga's vram.

Signed-off-by: Li Qiang <liqiang6-s@360.cn>

{ kraxel: with backward blits (negative pitch) addr is the topmost
          address, so check it as-is against vram size ]

Cc: qemu-stable@nongnu.org
Cc: P J P <ppandit@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wolfgang Bumiller <w.bumiller@proxmox.com>
Fixes: d3532a0db02296e687711b8cdc7791924efccea0 (CVE-2014-8106)
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1485938101-26602-1-git-send-email-kraxel@redhat.com
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
(cherry picked from commit 62d4c6bd5263bb8413a06c80144fc678df6dfb64)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---

diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
index 379910db2dc..629a5c8b4c6 100644
--- a/hw/display/cirrus_vga.c
+++ b/hw/display/cirrus_vga.c
@@ -277,10 +277,9 @@ static bool blit_region_is_unsafe(struct CirrusVGAState *s,
     }
     if (pitch < 0) {
         int64_t min = addr
-            + ((int64_t)s->cirrus_blt_height-1) * pitch;
-        int32_t max = addr
-            + s->cirrus_blt_width;
-        if (min < 0 || max > s->vga.vram_size) {
+            + ((int64_t)s->cirrus_blt_height - 1) * pitch
+            - s->cirrus_blt_width;
+        if (min < -1 || addr >= s->vga.vram_size) {
             return true;
         }
     } else {