From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54239) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eifHV-00048A-1B for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eifHS-0008Df-MU for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60612) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eifHS-0008DY-HQ for qemu-devel@nongnu.org; Mon, 05 Feb 2018 06:49:50 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B8DC8285BA for ; Mon, 5 Feb 2018 11:49:49 +0000 (UTC) From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Mon, 5 Feb 2018 11:49:37 +0000 Message-Id: <20180205114938.15784-4-berrange@redhat.com> In-Reply-To: <20180205114938.15784-1-berrange@redhat.com> References: <20180205114938.15784-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH 3/4] ui: check VNC audio frequency limit at time of reading from client List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Gerd Hoffmann , Laszlo Ersek , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= The 'vs->as.freq' value is a signed integer, which is read from an unsigned 32-bit int field on the wire. There is thus a risk of overflow on 32-bit platforms. Move the frequency limit checking to be done at time of read before casting to a signed integer. Reported-by: Laszlo Ersek Signed-off-by: Daniel P. Berrang=C3=A9 --- ui/vnc.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/ui/vnc.c b/ui/vnc.c index e14e524764..79ac9eccde 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -982,14 +982,7 @@ static void vnc_update_throttle_offset(VncState *vs) vs->client_width * vs->client_height * vs->client_pf.bytes_per_p= ixel; =20 if (vs->audio_cap) { - int freq =3D vs->as.freq; - /* We don't limit freq when reading settings from client, so - * it could be upto MAX_INT in size. 48khz is a sensible - * upper bound for trustworthy clients */ int bps; - if (freq > 48000) { - freq =3D 48000; - } switch (vs->as.fmt) { default: case AUD_FMT_U8: @@ -1005,7 +998,7 @@ static void vnc_update_throttle_offset(VncState *vs) bps =3D 4; break; } - offset +=3D freq * bps * vs->as.nchannels; + offset +=3D vs->as.freq * bps * vs->as.nchannels; } =20 /* Put a floor of 1MB on offset, so that if we have a large pending @@ -2279,6 +2272,7 @@ static int protocol_client_msg(VncState *vs, uint8_= t *data, size_t len) { int i; uint16_t limit; + uint32_t freq; VncDisplay *vd =3D vs->vd; =20 if (data[0] > 3) { @@ -2398,7 +2392,17 @@ static int protocol_client_msg(VncState *vs, uint8= _t *data, size_t len) vnc_client_error(vs); break; } - vs->as.freq =3D read_u32(data, 6); + freq =3D read_u32(data, 6); + /* No official limit for protocol, but 48khz is a sensib= le + * upper bound for trustworthy clients, and this limit + * protects calculations involving 'vs->as.freq' later. + */ + if (freq > 48000) { + VNC_DEBUG("Invalid audio frequency %u > 48000", freq= ); + vnc_client_error(vs); + break; + } + vs->as.freq =3D freq; break; default: VNC_DEBUG("Invalid audio message %d\n", read_u8(data, 4)= ); --=20 2.14.3