[Qemu-devel] [PATCH v2] net: rocker: fix an incorrect array bounds check

[P J P]

  Hello Paolo, all

Please see an updated patch below, as per suggestion in
  -> https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg04057.html

===
> From 344a487d637be20b3fb110bec36cb703e7f6ecaa Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <address@hidden>
Date: Wed, 23 Dec 2015 00:40:13 +0530
Subject: [PATCH v2] 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 <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
---
 hw/net/rocker/rocker.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/net/rocker/rocker.c b/hw/net/rocker/rocker.c
index c57f1a6..2e77e50 100644
--- 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) {
--
2.4.3
===


Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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