perf: fix buffer overflow error caused by specifying all tracepoints with -e option

Hi,

I found specifying all tracepoints within one "-e" option to perf top, separating each other with commas, will trigger a buffer overflow.

The command line is:

./perf to -e perf list |grep Tracepoint|awk -F'[' '{gsub(/[[:space:]]+/,"",$1);array[FNR]=$1}END{outputs=array[1];for (i=2;i<=FNR;i++){ outputs=outputs "," array[i];};print outputs}'

The error messages are:

*** buffer overflow detected ***: ./perf terminated ======= Backtrace: ========= /lib64/libc.so.6(__fortify_fail+0x37)[0x382cefb2c7] /lib64/libc.so.6[0x382cef91c0] /lib64/libc.so.6[0x382cef82f4] ./perf[0x424f9e]
./perf[0x425966]
./perf[0x42422b]
./perf[0x424468]
./perf[0x424a30]
./perf[0x41539a]
./perf[0x4056d4]
./perf[0x406126] /lib64/libc.so.6(__libc_start_main+0xfd)[0x382ce1ec5d] ./perf[0x405409]
======= Memory map: ========
00400000-0051c000 r-xp 00000000 fd:06 4573758 /home/hpt/temp/linux/perf/linux-2.6/tools/perf/perf
0071b000-00733000 rwxp 0011b000 fd:06 4573758 /home/hpt/temp/linux/perf/linux-2.6/tools/perf/perf
00733000-00b90000 rwxp 00000000 00:00 0
024dc000-024fd000 rwxp 00000000 00:00 0 [heap]
... ...

And I have a patch for fixing this problem. Please review it. Thanks.

I found when specifying all tracepoints with -e to one of subcommand, such as 'top', the program will trigger a buffer overflow error, like this:

*** buffer overflow detected ***: ./perf terminated
======= Backtrace: =========
/lib64/libc.so.6(__fortify_fail+0x37)[0x382cefb2c7] /lib64/libc.so.6[0x382cef91c0]
/lib64/libc.so.6[0x382cef82f4]
./perf[0x4250ee]
./perf[0x425ab6]
./perf[0x42437b]
./perf[0x4245b8]
./perf[0x424b80]
./perf[0x41548a]
./perf[0x405764]
./perf[0x4061b6]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x382ce1ec5d]
./perf[0x405499]
======= Memory map: ========
00400000-0051d000 r-xp 00000000 fd:06 4573549 /home/hpt/temp/linux/perf/linux-2.6/tools/perf/perf
....
The tracepoints are separated by comma, something like this:

perf top -e ...,kmem:kmalloc,kmem:kfree,kmem:kmem_cache_free,...

This comment will fix this problem.

The root reason of this problem is that store_event_type() is called with all the events, and will overflow the 'filename' at

    strncat(filename, orgname, strlen(orgname));

The comments will try to call store_event_type() when the event name has been found out.

---
 tools/perf/util/parse-events.c |   62 ++++++++++++++++++++--------------------
 1 files changed, 31 insertions(+), 31 deletions(-)

index c305305..7183fce 100644
@@ -491,6 +491,32 @@ parse_multiple_tracepoint_event(char *sys_name, const char *evt_exp,
 }
 
 
+static int store_event_type(const char *orgname)
+{
+	char filename[PATH_MAX], *c;
+	FILE *file;
+	int id, n;
+
+	sprintf(filename, "%s/", debugfs_path);
+	strncat(filename, orgname, strlen(orgname));
+	strcat(filename, "/id");
+
+	c = strchr(filename, ':');
+	if (c)
+		*c = '/';
+
+	file = fopen(filename, "r");
+	if (!file)
+		return 0;
+	n = fscanf(file, "%i", &id);
+	fclose(file);
+	if (n < 1) {
+		pr_err("cannot store event ID\n");
+		return -EINVAL;
+	}
+	return perf_header__push_event(id, orgname);
+}
+
 static enum event_result parse_tracepoint_event(const char **strp,
 				    struct perf_event_attr *attr)
 {

@@ -533,9 +559,13 @@ static enum event_result parse_tracepoint_event(const char **strp,
 		*strp += strlen(sys_name) + evt_length;
 		return parse_multiple_tracepoint_event(sys_name, evt_name,
 						       flags);
-	} else
+	} else {
+		if (store_event_type(evt_name) < 0)
+			return EVT_FAILED;
+
 		return parse_single_tracepoint_event(sys_name, evt_name,
 						     evt_length, attr, strp);
+	}
 }
 
 static enum event_result

@@ -778,41 +808,11 @@ modifier:
 	return ret;
 }
 
-static int store_event_type(const char *orgname)
-{
-	char filename[PATH_MAX], *c;
-	FILE *file;
-	int id, n;
-
-	sprintf(filename, "%s/", debugfs_path);
-	strncat(filename, orgname, strlen(orgname));
-	strcat(filename, "/id");
-
-	c = strchr(filename, ':');
-	if (c)
-		*c = '/';
-
-	file = fopen(filename, "r");
-	if (!file)
-		return 0;
-	n = fscanf(file, "%i", &id);
-	fclose(file);
-	if (n < 1) {
-		pr_err("cannot store event ID\n");
-		return -EINVAL;
-	}
-	return perf_header__push_event(id, orgname);
-}
-
 int parse_events(const struct option *opt __used, const char *str, int unset __used)
 {
 	struct perf_event_attr attr;
 	enum event_result ret;
 
-	if (strchr(str, ':'))
-		if (store_event_type(str) < 0)
-			return -1;
-
 	for (;;) {
 		if (nr_counters == MAX_COUNTERS)
 			return -1;

1.7.1