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tracing: Fix use-after-free in hist_unreg_all/hist_enable_unreg_all
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While running tools/testing/selftests test suite with KASAN, Dmitry
Vyukov hit the following use-after-free report:

  ==================================================================
  BUG: KASAN: use-after-free in hist_unreg_all+0x1a1/0x1d0 at addr
  ffff880031632cc0
  Read of size 8 by task ftracetest/7413
  ==================================================================
  BUG kmalloc-128 (Not tainted): kasan: bad access detected
  ------------------------------------------------------------------

This fixes the problem, along with the same problem in
hist_enable_unreg_all().

Link: http://lkml.kernel.org/r/c3d05b79e42555b6e36a3a99aae0e37315ee5304.1467247517.git.tom.zanussi@linux.intel.com

Cc: Dmitry Vyukov <[email protected]>
[Copied Steve's hist_enable_unreg_all() fix to hist_unreg_all()]
Signed-off-by: Tom Zanussi <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
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rostedt committed Aug 2, 2016
1 parent 377ccbb commit 47c1856
Showing 1 changed file with 4 additions and 4 deletions.
8 changes: 4 additions & 4 deletions kernel/trace/trace_events_hist.c
Original file line number Diff line number Diff line change
Expand Up @@ -1500,9 +1500,9 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,

static void hist_unreg_all(struct trace_event_file *file)
{
struct event_trigger_data *test;
struct event_trigger_data *test, *n;

list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry_safe(test, n, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
list_del_rcu(&test->list);
trace_event_trigger_enable_disable(file, 0);
Expand Down Expand Up @@ -1699,9 +1699,9 @@ hist_enable_get_trigger_ops(char *cmd, char *param)

static void hist_enable_unreg_all(struct trace_event_file *file)
{
struct event_trigger_data *test;
struct event_trigger_data *test, *n;

list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry_safe(test, n, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_HIST_ENABLE) {
list_del_rcu(&test->list);
update_cond_flag(file);
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