From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38231) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aL3eE-0005Z4-QJ for qemu-devel@nongnu.org; Mon, 18 Jan 2016 01:50:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aL3eD-000203-S0 for qemu-devel@nongnu.org; Mon, 18 Jan 2016 01:50:42 -0500 References: <1452764448-17953-1-git-send-email-mst@redhat.com> From: Jason Wang Message-ID: <569C8B29.4040300@redhat.com> Date: Mon, 18 Jan 2016 14:50:17 +0800 MIME-Version: 1.0 In-Reply-To: <1452764448-17953-1-git-send-email-mst@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] cadence_gem: fix buffer overflow List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" , qemu-devel@nongnu.org Cc: Alistair Francis , Prasad Pandit , =?UTF-8?B?5YiY5Luk?= , qemu-arm@nongnu.org, Peter Crosthwaite On 01/14/2016 05:43 PM, Michael S. Tsirkin wrote: > gem_receive copies a packet received from network into an rxbuf[2048] > array on stack, with size limited by descriptor length set by guest. I= f > guest is malicious and specifies a descriptor length that is too large, > and should packet size exceed array size, this results in a buffer > overflow. > > Reported-by: =E5=88=98=E4=BB=A4 > Signed-off-by: Michael S. Tsirkin > --- > hw/net/cadence_gem.c | 8 ++++++++ > 1 file changed, 8 insertions(+) Apply to my -net with tweak on commit log (changing receive to transmit as noticed). Thanks > > diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c > index 3639fc1..15a0786 100644 > --- a/hw/net/cadence_gem.c > +++ b/hw/net/cadence_gem.c > @@ -862,6 +862,14 @@ static void gem_transmit(CadenceGEMState *s) > break; > } > =20 > + if (tx_desc_get_length(desc) > sizeof(tx_packet) - (p - tx_pac= ket)) { > + DB_PRINT("TX descriptor @ 0x%x too large: size 0x%x space = 0x%x\n", > + (unsigned)packet_desc_addr, > + (unsigned)tx_desc_get_length(desc), > + sizeof(tx_packet) - (p - tx_packet)); > + break; > + } > + > /* Gather this fragment of the packet from "dma memory" to our= contig. > * buffer. > */