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

[ Upstream commit 59300b36f8 ]

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: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
pull/309/head^2
Steven Rostedt (VMware) 2021-03-30 09:58:38 -04:00 committed by Greg Kroah-Hartman
parent 6c6d583220
commit 1dcb3ebc24
1 changed files with 6 additions and 3 deletions
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9
kernel/trace/ftrace.c
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@ -3230,7 +3230,8 @@ ftrace_allocate_pages(unsigned long num_to_init)
pg = start_pg;
while (pg) {
order = get_count_order(pg->size / ENTRIES_PER_PAGE);
free_pages((unsigned long)pg->records, order);
if (order >= 0)
free_pages((unsigned long)pg->records, order);
start_pg = pg->next;
kfree(pg);
pg = start_pg;
@ -6452,7 +6453,8 @@ void ftrace_release_mod(struct module *mod)
clear_mod_from_hashes(pg);
order = get_count_order(pg->size / ENTRIES_PER_PAGE);
free_pages((unsigned long)pg->records, order);
if (order >= 0)
free_pages((unsigned long)pg->records, order);
tmp_page = pg->next;
kfree(pg);
ftrace_number_of_pages -= 1 << order;
@ -6812,7 +6814,8 @@ 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);
free_pages((unsigned long)pg->records, order);
if (order >= 0)
free_pages((unsigned long)pg->records, order);
ftrace_number_of_pages -= 1 << order;
ftrace_number_of_groups--;
kfree(pg);