[Xen-changelog] [xen-unstable] libxc: Fix checks on grant notify arguments

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
# Date 1322763612 0
# Node ID cc556b4cb3bec4e6b3be3c551590ab51b25052ef
# Parent  2618a5d6313d3c7defbf8f60d43d148595b934e0
libxc: Fix checks on grant notify arguments

The notify offset and event channels are both unsigned variables, so
testing for >= 0 will not correctly detect the use of -1 to indicate
the field is unused. Remove the useless comparison and replace with
correct range checks or comparisons to -1.

Reported-by: Anil Madhavapeddy <anil@xxxxxxxxxx>
Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---


diff -r 2618a5d6313d -r cc556b4cb3be tools/libxc/xc_linux_osdep.c
--- a/tools/libxc/xc_linux_osdep.c      Thu Dec 01 18:15:51 2011 +0000
+++ b/tools/libxc/xc_linux_osdep.c      Thu Dec 01 18:20:12 2011 +0000
@@ -566,7 +566,7 @@
         struct ioctl_gntdev_unmap_notify notify;
         notify.index = map->index;
         notify.action = 0;
-        if (notify_offset >= 0 && notify_offset < XC_PAGE_SIZE * count) {
+        if (notify_offset < XC_PAGE_SIZE * count) {
             notify.index += notify_offset;
             notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
         }
@@ -708,11 +708,11 @@
 
     notify.index = gref_info->index;
     notify.action = 0;
-    if (notify_offset >= 0) {
+    if (notify_offset < XC_PAGE_SIZE * count) {
         notify.index += notify_offset;
         notify.action |= UNMAP_NOTIFY_CLEAR_BYTE;
     }
-    if (notify_port >= 0) {
+    if (notify_port != -1) {
         notify.event_channel_port = notify_port;
         notify.action |= UNMAP_NOTIFY_SEND_EVENT;
     }

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