[Qemu-devel] [PATCH v2] net: imx: limit buffer descriptor count

[P J P <ppandit@redhat.com>]

From: Prasad J Pandit <pjp@fedoraproject.org>

i.MX Fast Ethernet Controller uses buffer descriptors to manage
data flow to/fro receive & transmit queues. While transmitting
packets, it could continue to read buffer descriptors if a buffer
descriptor has length of zero and has crafted values in bd.flags.
Set an upper limit to number of buffer descriptors.

Reported-by: Li Qiang <liqiang6-s@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
---
 hw/net/imx_fec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Update per
  -> https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg05284.html

diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c
index e60e338..547fa99 100644
--- a/hw/net/imx_fec.c
+++ b/hw/net/imx_fec.c
@@ -94,6 +94,8 @@ static const VMStateDescription vmstate_imx_fec = {
 #define PHY_INT_PARFAULT            (1 << 2)
 #define PHY_INT_AUTONEG_PAGE        (1 << 1)
 
+#define IMX_MAX_DESC                1024
+
 static void imx_fec_update(IMXFECState *s);
 
 /*
@@ -264,12 +266,12 @@ static void imx_fec_update(IMXFECState *s)
 
 static void imx_fec_do_tx(IMXFECState *s)
 {
-    int frame_size = 0;
+    int frame_size = 0, descnt = 0;
     uint8_t frame[FEC_MAX_FRAME_SIZE];
     uint8_t *ptr = frame;
     uint32_t addr = s->tx_descriptor;
 
-    while (1) {
+    while (descnt++ < IMX_MAX_DESC) {
         IMXFECBufDesc bd;
         int len;
 
-- 
2.5.5