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Subject[PATCH] perf: fix buffer overflow error caused by specifying all tracepoints with -e option
Date
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.

Signed-off-by: Han Pingtian <phan@redhat.com>
---
tools/perf/util/parse-events.c | 62 ++++++++++++++++++++--------------------
1 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index c305305..7183fce 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -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


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