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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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