From: Jiri Olsa <jolsa@redhat.com>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
mingo@elte.hu, Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCHv3] perf tools: Add struct ordered_events_buffer layer
Date: Thu, 6 Sep 2018 15:28:59 +0200 [thread overview]
Message-ID: <20180906132859.GA9577@krava> (raw)
In-Reply-To: <CABPqkBTiDYm_pbFdbQCiNTpECVpWyOb16vBFC7AZ=vzqcR=2ig@mail.gmail.com>
On Mon, Sep 03, 2018 at 07:37:56PM -0700, Stephane Eranian wrote:
SNIP
>
> I think the code is correct now for the issue related to uninitialized pointer.
> But there is still one problem I found stressing the code with max_alloc_size.
> The way the following is written:
>
> if (!list_empty(cache)) {
> new = list_entry(cache->next, struct ordered_event, list);
> list_del(&new->list);
> } else if (oe->buffer) {
> new = oe->buffer + oe->buffer_idx;
> if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
> oe->buffer = NULL;
> } else if (oe->cur_alloc_size < oe->max_alloc_size) {
> size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER *
> sizeof(*new);
>
> oe->buffer = malloc(size);
> if (!oe->buffer) {
> free_dup_event(oe, new_event);
> return NULL;
> }
>
> pr("alloc size %" PRIu64 "B (+%zu), max %" PRIu64 "B\n",
> oe->cur_alloc_size, size, oe->max_alloc_size);
>
> oe->cur_alloc_size += size;
>
> You can end up with oe->cur_alloc_size > oe->max_alloc_size in case
> the max limit is
> really low (< size_t size = sizeof (*oe->buffer) + MAX_SAMPLE_BUFFER *
> sizeof(*new);
> So I think to make sure you can never allocate more than the max, you
> have to do:
>
> size_t size = sizeof(*oe->buffer) MAX_SAMPLE_BUFFER * sizeof(*new);
> if (!list_empty(cache)) {
> new = list_entry(cache->next, struct ordered_event, list);
> list_del(&new->list);
> } else if (oe->buffer) {
> new = oe->buffer + oe->buffer_idx;
> if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
> oe->buffer = NULL;
> } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) {
>
> Then you will never allocate more than the max.
> I think with this change, we are okay.
> Tested-by: Stephane Eranian <eranian@google.com>
yep, makes sense.. something like below then
I'll post it on top of the previous patch
thanks,
jirka
---
diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 87171e8fd70d..2d1d0f3c8f77 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -101,6 +101,7 @@ static struct ordered_event *alloc_event(struct ordered_events *oe,
struct list_head *cache = &oe->cache;
struct ordered_event *new = NULL;
union perf_event *new_event;
+ size_t size;
new_event = dup_event(oe, event);
if (!new_event)
@@ -133,6 +134,8 @@ static struct ordered_event *alloc_event(struct ordered_events *oe,
* Removal of ordered event object moves it from events to
* the cache list.
*/
+ size = sizeof(*oe->buffer) + MAX_SAMPLE_BUFFER * sizeof(*new);
+
if (!list_empty(cache)) {
new = list_entry(cache->next, struct ordered_event, list);
list_del(&new->list);
@@ -140,10 +143,7 @@ static struct ordered_event *alloc_event(struct ordered_events *oe,
new = &oe->buffer->event[oe->buffer_idx];
if (++oe->buffer_idx == MAX_SAMPLE_BUFFER)
oe->buffer = NULL;
- } else if (oe->cur_alloc_size < oe->max_alloc_size) {
- size_t size = sizeof(*oe->buffer) +
- MAX_SAMPLE_BUFFER * sizeof(*new);
-
+ } else if ((oe->cur_alloc_size + size) < oe->max_alloc_size) {
oe->buffer = malloc(size);
if (!oe->buffer) {
free_dup_event(oe, new_event);
next prev parent reply other threads:[~2018-09-06 13:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-08 22:33 [PATCH v2] perf ordered_events: fix crash in free_dup_event() Stephane Eranian
2018-08-09 8:07 ` Jiri Olsa
2018-08-10 8:21 ` Stephane Eranian
2018-08-10 11:54 ` Jiri Olsa
2018-08-13 13:04 ` [PATCH] perf tools: Add struct ordered_events_buffer layer Jiri Olsa
2018-08-14 7:14 ` Stephane Eranian
2018-08-15 8:48 ` Jiri Olsa
2018-08-27 9:28 ` [PATCHv2] " Jiri Olsa
2018-08-27 11:07 ` Namhyung Kim
2018-08-27 15:24 ` Stephane Eranian
2018-08-27 17:05 ` [PATCHv3] " Jiri Olsa
2018-09-02 14:47 ` Jiri Olsa
2018-09-04 2:37 ` Stephane Eranian
2018-09-06 13:28 ` Jiri Olsa [this message]
2018-09-06 15:04 ` Stephane Eranian
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