From: Ian Campbell <ian.campbell@citrix.com>
Date: Wed, 17 Feb 2016 10:34:24 +0000 (+0000)
Subject: xl: NULL terminate buf when reading dom0 /proc/uptime
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~1622
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=8891dccfed78c6ee03b8912ed5353b83595a9549;p=xen.git

xl: NULL terminate buf when reading dom0 /proc/uptime

The contents of /proc/uptime is typically something like "80164.57
640617.58", so the existing 512 byte buffer is more than large enoguh,
so reduce its effective size to 511 bytes and ensure we include a
NULL.

Otherwise Coverity points out that we pass a potentially unterminated
string to strtok. In practice this likely doesn't actually cause
issues (at least on Linux) because the
string should always contain a space so we will stop parsing.

CID: 105590

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 4c03b2e76d..990d3c9f3a 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -6963,6 +6963,7 @@ static char *current_time_to_string(time_t now)
 static void print_dom0_uptime(int short_mode, time_t now)
 {
     int fd;
+    ssize_t nr;
     char buf[512];
     uint32_t uptime = 0;
     char *uptime_str = NULL;
@@ -6973,12 +6974,15 @@ static void print_dom0_uptime(int short_mode, time_t now)
     if (fd == -1)
         goto err;
 
-    if (read(fd, buf, sizeof(buf)) == -1) {
+    nr = read(fd, buf, sizeof(buf) - 1);
+    if (nr == -1) {
         close(fd);
         goto err;
     }
     close(fd);
 
+    buf[nr] = '\0';
+
     strtok(buf, " ");
     uptime = strtoul(buf, NULL, 10);