References: bsc#962627 CVE-2014-7815

Subject: vnc: sanitize bits_per_pixel from the client
From: Petr Matousek pmatouse@redhat.com Mon Oct 27 12:41:44 2014 +0100
Date: Tue Oct 28 11:51:04 2014 +0100:
Git: e6908bfe8e07f2b452e78e677da1b45b1c0f6829

bits_per_pixel that are less than 8 could result in accessing
non-initialized buffers later in the code due to the expectation
that bytes_per_pixel value that is used to initialize these buffers is
never zero.

To fix this check that bits_per_pixel from the client is one of the
values that the rfb protocol specification allows.

This is CVE-2014-7815.

Signed-off-by: Petr Matousek <pmatouse@redhat.com>

[ kraxel: apply codestyle fix ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Index: xen-4.6.1-testing/tools/qemu-xen-traditional-dir-remote/vnc.c
===================================================================
--- xen-4.6.1-testing.orig/tools/qemu-xen-traditional-dir-remote/vnc.c
+++ xen-4.6.1-testing/tools/qemu-xen-traditional-dir-remote/vnc.c
@@ -1643,6 +1643,16 @@ static void set_pixel_format(VncState *v
         return;
     }
 
+    switch (bits_per_pixel) {
+    case 8:
+    case 16:
+    case 32:
+        break;
+    default:
+        vnc_client_error(vs);
+        return;
+    }
+
     vs->clientds = vs->serverds;
     vs->clientds.pf.rmax = red_max ? red_max : 0xFF;
     count_bits(vs->clientds.pf.rbits, red_max);