If the processing of the tr->events loop fails, the filter that has been
added to filter_head will be released twice in free_filter_list(&head->rcu)
and __free_filter(filter).
After adding the filter of tr->events, add the filter to the filter_head
process to avoid triggering uaf.
Fixes: a9d0aab5eb33 ("tracing: Fix regression of filter waiting a long time on
RCU synchronization")
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=daba72c4af9915e9c894
Tested-by: [email protected]
Signed-off-by: Edward Adam Davis <[email protected]>
---
kernel/trace/trace_events_filter.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace_events_filter.c
b/kernel/trace/trace_events_filter.c
index 08141f105c95..3885aadc434d 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1436,13 +1436,6 @@ static void filter_free_subsystem_filters(struct
trace_subsystem_dir *dir,
INIT_LIST_HEAD(&head->list);
- item = kmalloc(sizeof(*item), GFP_KERNEL);
- if (!item)
- goto free_now;
-
- item->filter = filter;
- list_add_tail(&item->list, &head->list);
-
list_for_each_entry(file, &tr->events, list) {
if (file->system != dir)
continue;
@@ -1454,6 +1447,13 @@ static void filter_free_subsystem_filters(struct
trace_subsystem_dir *dir,
event_clear_filter(file);
}
+ item = kmalloc(sizeof(*item), GFP_KERNEL);
+ if (!item)
+ goto free_now;
+
+ item->filter = filter;
+ list_add_tail(&item->list, &head->list);
+
delay_free_filter(head);
return;
free_now:
--
2.43.0
