[Xen-changelog] [xen-unstable] xentop: fix NULL pointer dereference

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1274361007 -3600
# Node ID 11a3bf0e568ebc1e167740f51713a4a05e4e136d
# Parent  840f269d95fb8e7367753612fffabc521be8df9e
xentop: fix NULL pointer dereference

On my system, I'm getting SIGSEGVs in xentop because
xenstat_node_domain() is returning NULL.  Skip the loop if it does
rather than crashing.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 tools/xenstat/libxenstat/src/xenstat_linux.c |   28 ++++++++++++++-------------
 1 files changed, 15 insertions(+), 13 deletions(-)

diff -r 840f269d95fb -r 11a3bf0e568e 
tools/xenstat/libxenstat/src/xenstat_linux.c
--- a/tools/xenstat/libxenstat/src/xenstat_linux.c      Wed May 19 22:59:52 
2010 +0100
+++ b/tools/xenstat/libxenstat/src/xenstat_linux.c      Thu May 20 14:10:07 
2010 +0100
@@ -292,20 +292,22 @@ int xenstat_collect_networks(xenstat_nod
 
                /* If the device parsed is network bridge and both tx & rx 
packets are zero, we are most */
                /* likely using bonding so we alter the configuration for dom0 
to have bridge stats */
-               if ((strstr(iface, devBridge) != NULL) && (strstr(iface, 
devNoBridge) == NULL)) {
-                       domain = xenstat_node_domain(node, 0);
+               if ((strstr(iface, devBridge) != NULL) &&
+                   (strstr(iface, devNoBridge) == NULL) &&
+                   ((domain = xenstat_node_domain(node, 0)) != NULL)) {
                        for (i = 0; i < domain->num_networks; i++) {
-                               if ((domain->networks[i].id == 0) && 
(domain->networks[i].tbytes == 0)
-                                       && (domain->networks[i].rbytes == 0)) {
-                                               domain->networks[i].tbytes = 
txBytes;
-                                               domain->networks[i].tpackets = 
txPackets;
-                                               domain->networks[i].terrs = 
txErrs;
-                                               domain->networks[i].tdrop = 
txDrops;
-                                               domain->networks[i].rbytes = 
rxBytes;
-                                               domain->networks[i].rpackets = 
rxPackets;
-                                               domain->networks[i].rerrs = 
rxErrs;
-                                               domain->networks[i].rdrop = 
rxDrops;
-                               }
+                               if ((domain->networks[i].id != 0) ||
+                                   (domain->networks[i].tbytes != 0) ||
+                                   (domain->networks[i].rbytes != 0))
+                                       continue;
+                               domain->networks[i].tbytes = txBytes;
+                               domain->networks[i].tpackets = txPackets;
+                               domain->networks[i].terrs = txErrs;
+                               domain->networks[i].tdrop = txDrops;
+                               domain->networks[i].rbytes = rxBytes;
+                               domain->networks[i].rpackets = rxPackets;
+                               domain->networks[i].rerrs = rxErrs;
+                               domain->networks[i].rdrop = rxDrops;
                        }
                }
                else /* Otherwise we need to preserve old behaviour */

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