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

Date: Wed, 2 Mar 2016 17:29:58 +0530

Subject: [PATCH] net: check packet payload length

While computing IP checksum, 'net_checksum_calculate' reads

payload length from the packet. It could exceed the given 'data'

buffer size. Add a check to avoid it.

Reported-by: Liu Ling <liuling-it@360.cn>

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

Signed-off-by: Jason Wang <jasowang@redhat.com>

(cherry picked from commit 362786f14a753d8a5256ef97d7c10ed576d6572b)

---

 net/checksum.c | 10 ++++++++--

 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/checksum.c b/net/checksum.c

index 14c0855..0942437 100644

--- a/net/checksum.c

+++ b/net/checksum.c

@@ -59,6 +59,11 @@ void net_checksum_calculate(uint8_t *data, int length)

     int hlen, plen, proto, csum_offset;

     uint16_t csum;

+    /* Ensure data has complete L2 & L3 headers. */

+    if (length < 14 + 20) {

+        return;

+    }

+

     if ((data[14] & 0xf0) != 0x40)

 	return; /* not IPv4 */

     hlen  = (data[14] & 0x0f) * 4;

@@ -76,8 +81,9 @@ void net_checksum_calculate(uint8_t *data, int length)

 	return;

     }

-    if (plen < csum_offset+2)

-	return;

+    if (plen < csum_offset + 2 || 14 + hlen + plen > length) {

+        return;

+    }

     data[14+hlen+csum_offset]   = 0;

     data[14+hlen+csum_offset+1] = 0;