[PATCH] tracing: Fix filter logic error
From: Edward Adam Davis <hidden>
Date: 2025-06-24 06:52:33
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
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: syzbot+daba72c4af9915e9c894@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=daba72c4af9915e9c894
Tested-by: syzbot+daba72c4af9915e9c894@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <redacted>
---
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