diff options
| -rw-r--r-- | include/linux/mm.h | 2 | ||||
| -rw-r--r-- | include/linux/poison.h | 4 | ||||
| -rw-r--r-- | kernel/power/hibernate.c | 17 | ||||
| -rw-r--r-- | mm/Kconfig.debug | 14 | ||||
| -rw-r--r-- | mm/page_alloc.c | 11 | ||||
| -rw-r--r-- | mm/page_ext.c | 10 | ||||
| -rw-r--r-- | mm/page_poison.c | 7 |
7 files changed, 60 insertions, 5 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 99dcc8f36e28..b97243d6aa49 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2179,10 +2179,12 @@ extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, #ifdef CONFIG_PAGE_POISONING extern bool page_poisoning_enabled(void); extern void kernel_poison_pages(struct page *page, int numpages, int enable); +extern bool page_is_poisoned(struct page *page); #else static inline bool page_poisoning_enabled(void) { return false; } static inline void kernel_poison_pages(struct page *page, int numpages, int enable) { } +static inline bool page_is_poisoned(struct page *page) { return false; } #endif #ifdef CONFIG_DEBUG_PAGEALLOC diff --git a/include/linux/poison.h b/include/linux/poison.h index 4a27153574e2..51334edec506 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -30,7 +30,11 @@ #define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA) /********** mm/debug-pagealloc.c **********/ +#ifdef CONFIG_PAGE_POISONING_ZERO +#define PAGE_POISON 0x00 +#else #define PAGE_POISON 0xaa +#endif /********** mm/page_alloc.c ************/ diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index b7342a24f559..aa0f26b58426 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -1158,6 +1158,22 @@ static int __init kaslr_nohibernate_setup(char *str) return nohibernate_setup(str); } +static int __init page_poison_nohibernate_setup(char *str) +{ +#ifdef CONFIG_PAGE_POISONING_ZERO + /* + * The zeroing option for page poison skips the checks on alloc. + * since hibernation doesn't save free pages there's no way to + * guarantee the pages will still be zeroed. + */ + if (!strcmp(str, "on")) { + pr_info("Disabling hibernation due to page poisoning\n"); + return nohibernate_setup(str); + } +#endif + return 1; +} + __setup("noresume", noresume_setup); __setup("resume_offset=", resume_offset_setup); __setup("resume=", resume_setup); @@ -1166,3 +1182,4 @@ __setup("resumewait", resumewait_setup); __setup("resumedelay=", resumedelay_setup); __setup("nohibernate", nohibernate_setup); __setup("kaslr", kaslr_nohibernate_setup); +__setup("page_poison=", page_poison_nohibernate_setup); diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 1f99f9a0deae..5c50b238b770 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -65,3 +65,17 @@ config PAGE_POISONING_NO_SANITY If you are only interested in sanitization, say Y. Otherwise say N. + +config PAGE_POISONING_ZERO + bool "Use zero for poisoning instead of random data" + depends on PAGE_POISONING + ---help--- + Instead of using the existing poison value, fill the pages with + zeros. This makes it harder to detect when errors are occurring + due to sanitization but the zeroing at free means that it is + no longer necessary to write zeros when GFP_ZERO is used on + allocation. + + Enabling page poisoning with this option will disable hibernation + + If unsure, say N diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2a08349fbab2..50897dcaefdb 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1405,15 +1405,24 @@ static inline int check_new_page(struct page *page) return 0; } +static inline bool free_pages_prezeroed(bool poisoned) +{ + return IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) && + page_poisoning_enabled() && poisoned; +} + static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, int alloc_flags) { int i; + bool poisoned = true; for (i = 0; i < (1 << order); i++) { struct page *p = page + i; if (unlikely(check_new_page(p))) return 1; + if (poisoned) + poisoned &= page_is_poisoned(p); } set_page_private(page, 0); @@ -1424,7 +1433,7 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, kernel_poison_pages(page, 1 << order, 1); kasan_alloc_pages(page, order); - if (gfp_flags & __GFP_ZERO) + if (!free_pages_prezeroed(poisoned) && (gfp_flags & __GFP_ZERO)) for (i = 0; i < (1 << order); i++) clear_highpage(page + i); diff --git a/mm/page_ext.c b/mm/page_ext.c index 292ca7b8debd..2d864e64f7fe 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -106,12 +106,15 @@ struct page_ext *lookup_page_ext(struct page *page) struct page_ext *base; base = NODE_DATA(page_to_nid(page))->node_page_ext; -#ifdef CONFIG_DEBUG_VM +#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING) /* * The sanity checks the page allocator does upon freeing a * page can reach here before the page_ext arrays are * allocated when feeding a range of pages to the allocator * for the first time during bootup or memory hotplug. + * + * This check is also necessary for ensuring page poisoning + * works as expected when enabled */ if (unlikely(!base)) return NULL; @@ -180,12 +183,15 @@ struct page_ext *lookup_page_ext(struct page *page) { unsigned long pfn = page_to_pfn(page); struct mem_section *section = __pfn_to_section(pfn); -#ifdef CONFIG_DEBUG_VM +#if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING) /* * The sanity checks the page allocator does upon freeing a * page can reach here before the page_ext arrays are * allocated when feeding a range of pages to the allocator * for the first time during bootup or memory hotplug. + * + * This check is also necessary for ensuring page poisoning + * works as expected when enabled */ if (!section->page_ext) return NULL; diff --git a/mm/page_poison.c b/mm/page_poison.c index 89d3bc773633..479e7ea2bea6 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -71,11 +71,14 @@ static inline void clear_page_poison(struct page *page) __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } -static inline bool page_poison(struct page *page) +bool page_is_poisoned(struct page *page) { struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (!page_ext) + return false; + return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } @@ -137,7 +140,7 @@ static void unpoison_page(struct page *page) { void *addr; - if (!page_poison(page)) + if (!page_is_poisoned(page)) return; addr = kmap_atomic(page); |