Commit dffa1de0 authored by Daniel P. Berrangé's avatar Daniel P. Berrangé Committed by Gerd Hoffmann
Browse files

ui: avoid risk of 32-bit int overflow in VNC buffer check 



For very large framebuffers, it is theoretically possible for the result
of 'vs->throttle_output_offset * VNC_THROTTLE_OUTPUT_LIMIT_SCALE' to
exceed the size of a 32-bit int. For this to happen in practice, the
video RAM would have to be set to a large enough value, which is not
likely today. None the less we can be paranoid against future growth by
using division instead of multiplication when checking the limits.

Reported-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
Reviewed-by: default avatarLaszlo Ersek <lersek@redhat.com>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180205114938.15784-2-berrange@redhat.com
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 8dfa3061

ui/vnc.c

+2 −2
Original line number Diff line number Diff line
@@ -1579,8 +1579,8 @@ void vnc_write(VncState *vs, const void *data, size_t len) 
     * handshake, or from the job thread's VncState clone

     */

    if (vs->throttle_output_offset != 0 &&

        vs->output.offset > (vs->throttle_output_offset *

                             VNC_THROTTLE_OUTPUT_LIMIT_SCALE)) {

        (vs->output.offset / VNC_THROTTLE_OUTPUT_LIMIT_SCALE) >

        vs->throttle_output_offset) {

        trace_vnc_client_output_limit(vs, vs->ioc, vs->output.offset,

                                      vs->throttle_output_offset);

        vnc_disconnect_start(vs);