From d7f053652fef48bee7c461c162c8d4d2c96ab157 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 14 Jan 2016 11:43:30 +0200 Subject: [PATCH] cadence_gem: fix buffer overflow MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit gem_transmit copies a packet from guest into an tx_packet[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: 刘令 Signed-off-by: Michael S. Tsirkin Signed-off-by: Jason Wang --- 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 e513d9d..0346f3e 100644 --- a/hw/net/cadence_gem.c +++ b/hw/net/cadence_gem.c @@ -867,6 +867,14 @@ static void gem_transmit(CadenceGEMState *s) break; } + if (tx_desc_get_length(desc) > sizeof(tx_packet) - (p - tx_packet)) { + 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. */ -- 2.7.4