From 8a157d8a00e815cab4432653cb50c9cedbbb4931 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 10 Jun 2025 09:33:48 -0400 Subject: [PATCH] tracing: Do not free "head" on error path of filter_free_subsystem_filters() The variable "head" is allocated and initialized as a list before allocating the first "item" for the list. If the allocation of "item" fails, it frees "head" and then jumps to the label "free_now" which will process head and free it. This will cause a UAF of "head", and it doesn't need to free it before jumping to the "free_now" label as that code will free it. Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250610093348.33c5643a@gandalf.local.home Fixes: a9d0aab5eb33 ("tracing: Fix regression of filter waiting a long time on RCU synchronization") Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/202506070424.lCiNreTI-lkp@intel.com/ Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_filter.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index ea8b364b6818..08141f105c95 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -1437,10 +1437,8 @@ static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir, INIT_LIST_HEAD(&head->list); item = kmalloc(sizeof(*item), GFP_KERNEL); - if (!item) { - kfree(head); + if (!item) goto free_now; - } item->filter = filter; list_add_tail(&item->list, &head->list); -- 2.25.1