From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Fri, 8 Apr 2016 06:03:48 +0000 (+0530)
Subject: net: stellaris_enet: check packet length against receive buffer
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3a15cc0e1ee7168db0782133d2607a6bfa422d66;p=qemu.git

net: stellaris_enet: check packet length against receive buffer

When receiving packets over Stellaris ethernet controller, it
uses receive buffer of size 2048 bytes. In case the controller
accepts large(MTU) packets, it could lead to memory corruption.
Add check to avoid it.

Reported-by: Oleksandr Bazhaniuk <oleksandr.bazhaniuk@intel.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1460095428-22698-1-git-send-email-ppandit@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---

diff --git a/hw/net/stellaris_enet.c b/hw/net/stellaris_enet.c
index 84cf60b303..6880894945 100644
--- a/hw/net/stellaris_enet.c
+++ b/hw/net/stellaris_enet.c
@@ -236,8 +236,18 @@ static ssize_t stellaris_enet_receive(NetClientState *nc, const uint8_t *buf, si
     n = s->next_packet + s->np;
     if (n >= 31)
         n -= 31;
-    s->np++;
 
+    if (size >= sizeof(s->rx[n].data) - 6) {
+        /* If the packet won't fit into the
+         * emulated 2K RAM, this is reported
+         * as a FIFO overrun error.
+         */
+        s->ris |= SE_INT_FOV;
+        stellaris_enet_update(s);
+        return -1;
+    }
+
+    s->np++;
     s->rx[n].len = size + 6;
     p = s->rx[n].data;
     *(p++) = (size + 6);