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PM: hibernate: fix crashes with init_on_free=1 

Upon resuming from hibernation, free pages may contain stale data from
the kernel that initiated the resume. This breaks the invariant
inflicted by init_on_free=1 that freed pages must be zeroed.

To deal with this problem, make clear_free_pages() also clear the free
pages when init_on_free is enabled.

Fixes: 6471384af2 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Reported-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: 5.3+ <stable@vger.kernel.org> # 5.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Alexander Potapenko 2020-01-16 12:09:34 +01:00 committed by Rafael J. Wysocki
parent b3a987b026
commit 18451f9f9e
1 changed files with 10 additions and 10 deletions
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20
kernel/power/snapshot.c
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@ -1147,24 +1147,24 @@ void free_basic_memory_bitmaps(void)
void clear_free_pages(void)
{
#ifdef CONFIG_PAGE_POISONING_ZERO
struct memory_bitmap *bm = free_pages_map;
unsigned long pfn;
if (WARN_ON(!(free_pages_map)))
return;
memory_bm_position_reset(bm);
pfn = memory_bm_next_pfn(bm);
while (pfn != BM_END_OF_MAP) {
if (pfn_valid(pfn))
clear_highpage(pfn_to_page(pfn));
if (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) || want_init_on_free()) {
memory_bm_position_reset(bm);
pfn = memory_bm_next_pfn(bm);
while (pfn != BM_END_OF_MAP) {
if (pfn_valid(pfn))
clear_highpage(pfn_to_page(pfn));
pfn = memory_bm_next_pfn(bm);
}
memory_bm_position_reset(bm);
pr_info("free pages cleared after restore\n");
}
memory_bm_position_reset(bm);
pr_info("free pages cleared after restore\n");
#endif /* PAGE_POISONING_ZERO */
}
/**