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Subject[PATCH 04/13] perf ordered_events: Prevent crossing max_alloc_size
Date
From: Jiri Olsa <jolsa@kernel.org>

Stephane reported a possible issue in the ordered events code, which
could lead to allocating more memory than guarded by max_alloc_size.

He also suggested the fix to properly check that the new size is below
the max_alloc_size limit.

Reported-by: Stephane Eranian <eranian@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180907102455.7030-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/ordered-events.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 84ce25272c13..1904e7f6ec84 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);
--
2.14.4
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