From: Alexander Potapenko glider@google.com
commit 18451f9f9e5810b8bd1245c5ae166f257e0e2b9d upstream.
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: 6471384af2a6 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/power/snapshot.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
--- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -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 */ }
/**