lkml.org 
[lkml]   [2009]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH][GIT PULL] tracing: fix memory leak in trace_stat

Ingo,

Please pull the latest tip/tracing/ftrace tree, which can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/ftrace


Steven Rostedt (1):
tracing: fix memory leak in trace_stat

----
kernel/trace/trace_stat.c | 23 +++++++++++++----------
1 files changed, 13 insertions(+), 10 deletions(-)
---------------------------
commit 38c007b2f0b40747074508d8304f2cb01148fb05
Author: Steven Rostedt <srostedt@redhat.com>
Date: Sat Mar 21 02:44:50 2009 -0400

tracing: fix memory leak in trace_stat

If the function profiler does not have any items recorded and one were
to cat the function stat file, the kernel would take a BUG with a NULL
pointer dereference.

Looking further into this, I found that returning NULL from stat_start
did not stop the stat logic, and would later call stat_next. This breaks
from the way seq_file works, so I looked into fixing the stat code.

This is where I noticed that the last next_entry is never freed.
It is allocated, and if the stat_next returns NULL, the code breaks out
of the loop, unlocks the mutex and exits. We never link the next_entry
nor do we free it. Thus it is a real memory leak.

This patch rearranges the code a bit to not only fix the memory leak,
but also to act more like seq_file where nothing is printed if there
is nothing to print. That is, stat_start returns NULL.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 39310e3..f71b85b 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -75,7 +75,7 @@ static int stat_seq_init(struct tracer_stat_session *session)
{
struct trace_stat_list *iter_entry, *new_entry;
struct tracer_stat *ts = session->ts;
- void *prev_stat;
+ void *stat;
int ret = 0;
int i;

@@ -85,6 +85,10 @@ static int stat_seq_init(struct tracer_stat_session *session)
if (!ts->stat_cmp)
ts->stat_cmp = dummy_cmp;

+ stat = ts->stat_start();
+ if (!stat)
+ goto exit;
+
/*
* The first entry. Actually this is the second, but the first
* one (the stat_list head) is pointless.
@@ -99,14 +103,19 @@ static int stat_seq_init(struct tracer_stat_session *session)

list_add(&new_entry->list, &session->stat_list);

- new_entry->stat = ts->stat_start();
- prev_stat = new_entry->stat;
+ new_entry->stat = stat;

/*
* Iterate over the tracer stat entries and store them in a sorted
* list.
*/
for (i = 1; ; i++) {
+ stat = ts->stat_next(stat, i);
+
+ /* End of insertion */
+ if (!stat)
+ break;
+
new_entry = kmalloc(sizeof(struct trace_stat_list), GFP_KERNEL);
if (!new_entry) {
ret = -ENOMEM;
@@ -114,11 +123,7 @@ static int stat_seq_init(struct tracer_stat_session *session)
}

INIT_LIST_HEAD(&new_entry->list);
- new_entry->stat = ts->stat_next(prev_stat, i);
-
- /* End of insertion */
- if (!new_entry->stat)
- break;
+ new_entry->stat = stat;

list_for_each_entry(iter_entry, &session->stat_list, list) {

@@ -137,8 +142,6 @@ static int stat_seq_init(struct tracer_stat_session *session)
break;
}
}
-
- prev_stat = new_entry->stat;
}
exit:
mutex_unlock(&session->stat_mutex);


\
 
 \ /
  Last update: 2009-03-21 07:57    [W:0.057 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site