From: P J P <pjp@fedoraproject.org>

Date: Tue, 15 Sep 2015 16:40:49 +0530

Subject: [PATCH] net: add checks to validate ring buffer

 pointers(CVE-2015-5279)

Ne2000 NIC uses ring buffer of NE2000_MEM_SIZE(49152)

bytes to process network packets. While receiving packets

via ne2000_receive() routine, a local 'index' variable

could exceed the ring buffer size, which could lead to a

memory buffer overflow. Added other checks at initialisation.

Reported-by: Qinghao Tang <luodalongde@gmail.com>

Signed-off-by: P J P <pjp@fedoraproject.org>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 9bbdbc66e5765068dce76e9269dce4547afd8ad4)

---

 hw/net/ne2000.c | 19 +++++++++++++++----

 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/hw/net/ne2000.c b/hw/net/ne2000.c

index 44a4264..2bdb4c9 100644

--- a/hw/net/ne2000.c

+++ b/hw/net/ne2000.c

@@ -230,6 +230,9 @@ ssize_t ne2000_receive(NetClientState *nc, const uint8_t *buf, size_t size_)

     }

     index = s->curpag << 8;

+    if (index >= NE2000_PMEM_END) {

+        index = s->start;

+    }

     /* 4 bytes for header */

     total_len = size + 4;

     /* address for next packet (4 bytes for CRC) */

@@ -315,13 +318,19 @@ static void ne2000_ioport_write(void *opaque, uint32_t addr, uint32_t val)

         offset = addr | (page << 4);

         switch(offset) {

         case EN0_STARTPG:

-            s->start = val << 8;

+            if (val << 8 <= NE2000_PMEM_END) {

+                s->start = val << 8;

+            }

             break;

         case EN0_STOPPG:

-            s->stop = val << 8;

+            if (val << 8 <= NE2000_PMEM_END) {

+                s->stop = val << 8;

+            }

             break;

         case EN0_BOUNDARY:

-            s->boundary = val;

+            if (val << 8 < NE2000_PMEM_END) {

+                s->boundary = val;

+            }

             break;

         case EN0_IMR:

             s->imr = val;

@@ -362,7 +371,9 @@ static void ne2000_ioport_write(void *opaque, uint32_t addr, uint32_t val)

             s->phys[offset - EN1_PHYS] = val;

             break;

         case EN1_CURPAG:

-            s->curpag = val;

+            if (val << 8 < NE2000_PMEM_END) {

+                s->curpag = val;

+            }

             break;

         case EN1_MULT ... EN1_MULT + 7:

             s->mult[offset - EN1_MULT] = val;