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From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Fri, 8 Apr 2016 11:33:48 +0530
Subject: [PATCH] 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>
(cherry picked from commit 3a15cc0e1ee7168db0782133d2607a6bfa422d66)
---
 hw/net/stellaris_enet.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/hw/net/stellaris_enet.c b/hw/net/stellaris_enet.c
index 278a654..90ada81 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);