From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43903) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aJeRR-0006GA-Vl for qemu-devel@nongnu.org; Thu, 14 Jan 2016 04:43:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aJeRR-0004m8-71 for qemu-devel@nongnu.org; Thu, 14 Jan 2016 04:43:41 -0500 Date: Thu, 14 Jan 2016 11:43:30 +0200 From: "Michael S. Tsirkin" Message-ID: <1452764448-17953-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH] cadence_gem: fix buffer overflow List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Crosthwaite , Jason Wang , Prasad Pandit , qemu-arm@nongnu.org, =?us-ascii?B?PT9VVEYtOD9xPz1FNT04OD05OD1FND1CQj1BND89?= , Alistair Francis gem_receive copies a packet received from network into an rxbuf[2048] array on stack, with size limited by descriptor length set by guest. If 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(+) 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_packe= t)) { + 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 c= ontig. * buffer. */ --=20 MST