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mon_procd: fix parsing of /proc/<pid>/stat

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The output of /proc/<pid>/stat will show the process name in parentheses.
The parsing code in read_stat() tries to filter out the parentheses, which
will go wrong when the process name itself also contains parentheses, e.g.
in an output like this: "2421 ((sd-pam)) S 2420 2420 2420 ..."

In this case, the first closing parentheses will be taken as end marker,
and the sscanf() on the remaining string will silently fail, leaving its
values in uninitialized state and producing wrong data.

Fix this by using strrchr() instead of strchr() to find the last closing
parentheses. Also add return value checking for sscanf() and initialize the
values to 0.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Gerald Schaefer
2018-06-27 19:32:31 +02:00
committed by Jan Höppner
parent d36ff82999
commit 58ecf1f363
2 changed files with 9 additions and 5 deletions
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CHANGELOG.md
+1
View File
@@ -7,6 +7,7 @@ Release history for s390-tools (MIT version)
Changes of existing tools:
Bug Fixes:
- mon_procd: fix parsing of /proc/<pid>/stat
* __v2.5.0 (2018-06-08)__
mon_tools/mon_procd.c
+8 -5
View File
@@ -594,17 +594,18 @@ static void cal_task_pcpu(struct task_t *task, const unsigned long long tics)
*/
static int read_stat(struct task_t *task)
{
int ppid, tty, proc;
unsigned long flags, pri, nice;
unsigned long long maj_flt, utime, stime, cutime, cstime;
unsigned long long maj_flt = 0, utime = 0, stime = 0, cutime = 0,
cstime = 0;
unsigned long flags = 0, pri = 0, nice = 0;
char *cmd_start, *cmd_end, *cmdlenp, *cmdp;
int ppid = 0, tty = 0, proc = 0, rc;
snprintf(fname, sizeof(fname), "/proc/%u/stat", task->pid);
if (read_file(fname, buf, sizeof(buf) - 1) == -1)
return 0;
cmd_start = strchr(buf, '(') + 1;
cmd_end = strchr(cmd_start, ')');
cmd_end = strrchr(cmd_start, ')');
name_lens.cmd_len = cmd_end - cmd_start;
cmdlenp = mon_record + sizeof(struct monwrite_hdr);
cmdlenp += sizeof(struct procd_hdr);
@@ -625,7 +626,7 @@ static int read_stat(struct task_t *task)
memcpy(cmdlenp, &name_lens.cmd_len, sizeof(__u16));
cmd_end += 2;
sscanf(cmd_end,
rc = sscanf(cmd_end,
"%c %d %*d %*d %d %*d "
"%lu %*s %*s %Lu %*s "
"%Lu %Lu %Lu %Lu "
@@ -642,6 +643,8 @@ static int read_stat(struct task_t *task)
&utime, &stime, &cutime, &cstime,
&pri, &nice,
&proc);
if (rc != 12)
syslog(LOG_ERR, "bad data in %s \n", fname);
task->ppid = (__u32)ppid;
task->tty = (__u16)tty;
task->flags = (__u32)flags;