diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig.debug | 25 | ||||
| -rw-r--r-- | mm/Makefile | 2 | ||||
| -rw-r--r-- | mm/page_alloc.c | 2 | ||||
| -rw-r--r-- | mm/page_poison.c (renamed from mm/debug-pagealloc.c) | 60 |
4 files changed, 75 insertions, 14 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index a0c136af9c91..1f99f9a0deae 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -41,4 +41,27 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT can be overridden by debug_pagealloc=off|on. config PAGE_POISONING - bool + bool "Poison pages after freeing" + select PAGE_EXTENSION + select PAGE_POISONING_NO_SANITY if HIBERNATION + ---help--- + Fill the pages with poison patterns after free_pages() and verify + the patterns before alloc_pages. The filling of the memory helps + reduce the risk of information leaks from freed data. This does + have a potential performance impact. + + Note that "poison" here is not the same thing as the "HWPoison" + for CONFIG_MEMORY_FAILURE. This is software poisoning only. + + If unsure, say N + +config PAGE_POISONING_NO_SANITY + depends on PAGE_POISONING + bool "Only poison, don't sanity check" + ---help--- + Skip the sanity checking on alloc, only fill the pages with + poison on free. This reduces some of the overhead of the + poisoning feature. + + If you are only interested in sanitization, say Y. Otherwise + say N. diff --git a/mm/Makefile b/mm/Makefile index 2ed43191fc3b..cfdd481d27a5 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -48,7 +48,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o obj-$(CONFIG_SLOB) += slob.o obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o obj-$(CONFIG_KSM) += ksm.o -obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o +obj-$(CONFIG_PAGE_POISONING) += page_poison.o obj-$(CONFIG_SLAB) += slab.o obj-$(CONFIG_SLUB) += slub.o obj-$(CONFIG_KMEMCHECK) += kmemcheck.o diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0691403aed93..2a08349fbab2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1025,6 +1025,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) PAGE_SIZE << order); } arch_free_page(page, order); + kernel_poison_pages(page, 1 << order, 0); kernel_map_pages(page, 1 << order, 0); return true; @@ -1420,6 +1421,7 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags, arch_alloc_page(page, order); kernel_map_pages(page, 1 << order, 1); + kernel_poison_pages(page, 1 << order, 1); kasan_alloc_pages(page, order); if (gfp_flags & __GFP_ZERO) diff --git a/mm/debug-pagealloc.c b/mm/page_poison.c index 5bf5906ce13b..89d3bc773633 100644 --- a/mm/debug-pagealloc.c +++ b/mm/page_poison.c @@ -6,22 +6,48 @@ #include <linux/poison.h> #include <linux/ratelimit.h> -static bool page_poisoning_enabled __read_mostly; +static bool __page_poisoning_enabled __read_mostly; +static bool want_page_poisoning __read_mostly; -static bool need_page_poisoning(void) +static int early_page_poison_param(char *buf) { - if (!debug_pagealloc_enabled()) - return false; + if (!buf) + return -EINVAL; + + if (strcmp(buf, "on") == 0) + want_page_poisoning = true; + else if (strcmp(buf, "off") == 0) + want_page_poisoning = false; - return true; + return 0; +} +early_param("page_poison", early_page_poison_param); + +bool page_poisoning_enabled(void) +{ + return __page_poisoning_enabled; +} + +static bool need_page_poisoning(void) +{ + return want_page_poisoning; } static void init_page_poisoning(void) { - if (!debug_pagealloc_enabled()) - return; + /* + * page poisoning is debug page alloc for some arches. If either + * of those options are enabled, enable poisoning + */ + if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC)) { + if (!want_page_poisoning && !debug_pagealloc_enabled()) + return; + } else { + if (!want_page_poisoning) + return; + } - page_poisoning_enabled = true; + __page_poisoning_enabled = true; } struct page_ext_operations page_poisoning_ops = { @@ -83,6 +109,9 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) unsigned char *start; unsigned char *end; + if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)) + return; + start = memchr_inv(mem, PAGE_POISON, bytes); if (!start) return; @@ -95,9 +124,9 @@ static void check_poison_mem(unsigned char *mem, size_t bytes) if (!__ratelimit(&ratelimit)) return; else if (start == end && single_bit_flip(*start, PAGE_POISON)) - printk(KERN_ERR "pagealloc: single bit error\n"); + pr_err("pagealloc: single bit error\n"); else - printk(KERN_ERR "pagealloc: memory corruption\n"); + pr_err("pagealloc: memory corruption\n"); print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, end - start + 1, 1); @@ -125,9 +154,9 @@ static void unpoison_pages(struct page *page, int n) unpoison_page(page + i); } -void __kernel_map_pages(struct page *page, int numpages, int enable) +void kernel_poison_pages(struct page *page, int numpages, int enable) { - if (!page_poisoning_enabled) + if (!page_poisoning_enabled()) return; if (enable) @@ -135,3 +164,10 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) else poison_pages(page, numpages); } + +#ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC +void __kernel_map_pages(struct page *page, int numpages, int enable) +{ + /* This function does nothing, all work is done via poison pages */ +} +#endif |