vnc: sanitize bits_per_pixel from the client

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>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Conflicts:
	ui/vnc.c

diff --git a/ui/vnc.c b/ui/vnc.c
index 40018f70f1bc5b3139e4d11d4e891211f6a5bc5c..46a9c888ad9043ffc635249dc570ad4435ee66cc 100644 (file)
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1827,6 +1827,16 @@ static void set_pixel_format(VncState *vs,
         return;
     }
 
+    switch (bits_per_pixel) {
+    case 8:
+    case 16:
+    case 32:
+        break;
+    default:
+        vnc_client_error(vs);
+        return;
+    }
+
     vs->clientds = *(vs->vd->guest.ds);
     vs->clientds.pf.rmax = red_max;
     vs->clientds.pf.rbits = hweight_long(red_max);