Commit 59300b36 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

ftrace: Check if pages were allocated before calling free_pages() 

It is possible that on error pg->size can be zero when getting its order,
which would return a -1 value. It is dangerous to pass in an order of -1
to free_pages(). Check if order is greater than or equal to zero before
calling free_pages().

Link: https://lore.kernel.org/lkml/20210330093916.432697c7@gandalf.local.home/



Reported-by: default avatarAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 83b62687

kernel/trace/ftrace.c

+6 −3
Original line number Diff line number Diff line
@@ -3231,6 +3231,7 @@ ftrace_allocate_pages(unsigned long num_to_init) 
	pg = start_pg;

	while (pg) {

		order = get_count_order(pg->size / ENTRIES_PER_PAGE);

		if (order >= 0)

			free_pages((unsigned long)pg->records, order);

		start_pg = pg->next;

		kfree(pg);
@@ -6418,6 +6419,7 @@ void ftrace_release_mod(struct module *mod) 
		clear_mod_from_hashes(pg);



		order = get_count_order(pg->size / ENTRIES_PER_PAGE);

		if (order >= 0)

			free_pages((unsigned long)pg->records, order);

		tmp_page = pg->next;

		kfree(pg);
@@ -6778,6 +6780,7 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) 
		if (!pg->index) {

			*last_pg = pg->next;

			order = get_count_order(pg->size / ENTRIES_PER_PAGE);

			if (order >= 0)

				free_pages((unsigned long)pg->records, order);

			ftrace_number_of_pages -= 1 << order;

			ftrace_number_of_groups--;