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>

diff --git a/hw/net/rocker/rocker.c b/hw/net/rocker/rocker.c
index 47d080fd33f54eb27bd69656c46ccf1301297243..7e4ec0a747da9fe1c6b3589c97761b9d6a3197e0 100644 (file)
--- a/hw/net/rocker/rocker.c
+++ b/hw/net/rocker/rocker.c
@@ -234,6 +234,9 @@ 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) {
@@ -246,10 +249,7 @@ 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) {