net: rocker: fix an incorrect array bounds check

While processing transmit(tx) descriptors in 'tx_consume' routine
the switch emulator suffers from an off-by-one error, if a
descriptor was to have more than allowed(ROCKER_TX_FRAGS_MAX=16)
fragments. Fix an incorrect bounds check to avoid it.

Reported-by: Qinghao Tang <luodalongde@gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit 007cd223de527b5f41278f2d886c1a4beb3e67aa)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/net/rocker/rocker.c b/hw/net/rocker/rocker.c
index c57f1a661a93f838c7ae4813ac9fae0952af889e..2e77e5086abfbde01cf46866209071fe19db73f6 100644 (file)
--- a/hw/net/rocker/rocker.c
+++ b/hw/net/rocker/rocker.c
@@ -232,6 +232,9 @@ static int tx_consume(Rocker *r, DescInfo *info)
         frag_addr = rocker_tlv_get_le64(tlvs[ROCKER_TLV_TX_FRAG_ATTR_ADDR]);
         frag_len = rocker_tlv_get_le16(tlvs[ROCKER_TLV_TX_FRAG_ATTR_LEN]);
 
+        if (iovcnt >= ROCKER_TX_FRAGS_MAX) {
+            goto err_too_many_frags;
+        }
         iov[iovcnt].iov_len = frag_len;
         iov[iovcnt].iov_base = g_malloc(frag_len);
         if (!iov[iovcnt].iov_base) {
@@ -244,10 +247,7 @@ static int tx_consume(Rocker *r, DescInfo *info)
             err = -ROCKER_ENXIO;
             goto err_bad_io;
         }
-
-        if (++iovcnt > ROCKER_TX_FRAGS_MAX) {
-            goto err_too_many_frags;
-        }
+        iovcnt++;
     }
 
     if (iovcnt) {