[libvirt] [PATCH 2/5] openvzGetProcessInfo: address clang-detected low-probability flaw
From: Jim Meyering <meyering(a)redhat.com>
* src/openvz/openvz_driver.c (openvzGetProcessInfo): Reorganize
so that unexpected /proc/vz/vestat content cannot make us use
uninitialized variables. Without this change, an input line with
a matching "readvps", but fewer than 4 numbers would result in our
using at least "systime" uninitialized.
---
src/openvz/openvz_driver.c | 30 +++++++++++++++---------------
1 files changed, 15 insertions(+), 15 deletions(-)
diff --git a/src/openvz/openvz_driver.c b/src/openvz/openvz_driver.c
index 95c4236..47004d6 100644
--- a/src/openvz/openvz_driver.c
+++ b/src/openvz/openvz_driver.c
@@ -1384,14 +1384,15 @@ static int openvzGetProcessInfo(unsigned long long *cpuTime, int
vpsid) {
int fd;
char line[1024] ;
unsigned long long usertime, systime, nicetime;
- int readvps = 0, ret;
+ int readvps = vpsid + 1; /* ensure readvps is initially different */
+ int ret;
/* read statistic from /proc/vz/vestat.
sample:
Version: 2.2
- VEID user nice system uptime idle other..
- 33 78 0 1330 59454597 142650441835148 other..
- 55 178 0 5340 59424597 542650441835148 other..
+ VEID user nice system uptime idle other..
+ 33 78 0 1330 59454597 142650441835148 other..
+ 55 178 0 5340 59424597 542650441835148 other..
*/
if ((fd = open("/proc/vz/vestat", O_RDONLY)) == -1)
@@ -1400,15 +1401,18 @@ Version: 2.2
/*search line with VEID=vpsid*/
while(1) {
ret = openvz_readline(fd, line, sizeof(line));
- if(ret <= 0)
+ if (ret <= 0)
break;
- if (sscanf(line, "%d %llu %llu %llu",
- &readvps, &usertime, &nicetime, &systime) !=
4)
- continue;
-
- if (readvps == vpsid)
- break; /*found vpsid*/
+ if (sscanf (line, "%d %llu %llu %llu",
+ &readvps, &usertime, &nicetime, &systime) == 4
+ && readvps == vpsid) { /*found vpsid*/
+ /* convert jiffies to nanoseconds */
+ *cpuTime = (1000ull * 1000ull * 1000ull
+ * (usertime + nicetime + systime)
+ / (unsigned long long)sysconf(_SC_CLK_TCK));
+ break;
+ }
}
close(fd);
@@ -1418,10 +1422,6 @@ Version: 2.2
if (readvps != vpsid) /*not found*/
return -1;
- /* convert jiffies to nanoseconds */
- *cpuTime = 1000ull * 1000ull * 1000ull * (usertime + nicetime + systime)
- / (unsigned long long)sysconf(_SC_CLK_TCK);
-
return 0;
}
--
1.7.1.rc1.248.gcefbb