diff options
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/common.c | 9 | ||||
| -rw-r--r-- | mm/kasan/hw_tags.c | 60 | ||||
| -rw-r--r-- | mm/kasan/kasan.h | 27 |
3 files changed, 94 insertions, 2 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 833bf2cfd2a3..1d0008e1c420 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -95,19 +95,24 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark) } #endif /* CONFIG_KASAN_STACK */ -void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init) +bool __kasan_unpoison_pages(struct page *page, unsigned int order, bool init) { u8 tag; unsigned long i; if (unlikely(PageHighMem(page))) - return; + return false; + + if (!kasan_sample_page_alloc(order)) + return false; tag = kasan_random_tag(); kasan_unpoison(set_tag(page_address(page), tag), PAGE_SIZE << order, init); for (i = 0; i < (1 << order); i++) page_kasan_tag_set(page + i, tag); + + return true; } void __kasan_poison_pages(struct page *page, unsigned int order, bool init) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index b22c4f461cb0..d1bcb0205327 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -59,6 +59,24 @@ EXPORT_SYMBOL_GPL(kasan_mode); /* Whether to enable vmalloc tagging. */ DEFINE_STATIC_KEY_TRUE(kasan_flag_vmalloc); +#define PAGE_ALLOC_SAMPLE_DEFAULT 1 +#define PAGE_ALLOC_SAMPLE_ORDER_DEFAULT 3 + +/* + * Sampling interval of page_alloc allocation (un)poisoning. + * Defaults to no sampling. + */ +unsigned long kasan_page_alloc_sample = PAGE_ALLOC_SAMPLE_DEFAULT; + +/* + * Minimum order of page_alloc allocations to be affected by sampling. + * The default value is chosen to match both + * PAGE_ALLOC_COSTLY_ORDER and SKB_FRAG_PAGE_ORDER. + */ +unsigned int kasan_page_alloc_sample_order = PAGE_ALLOC_SAMPLE_ORDER_DEFAULT; + +DEFINE_PER_CPU(long, kasan_page_alloc_skip); + /* kasan=off/on */ static int __init early_kasan_flag(char *arg) { @@ -122,6 +140,48 @@ static inline const char *kasan_mode_info(void) return "sync"; } +/* kasan.page_alloc.sample=<sampling interval> */ +static int __init early_kasan_flag_page_alloc_sample(char *arg) +{ + int rv; + + if (!arg) + return -EINVAL; + + rv = kstrtoul(arg, 0, &kasan_page_alloc_sample); + if (rv) + return rv; + + if (!kasan_page_alloc_sample || kasan_page_alloc_sample > LONG_MAX) { + kasan_page_alloc_sample = PAGE_ALLOC_SAMPLE_DEFAULT; + return -EINVAL; + } + + return 0; +} +early_param("kasan.page_alloc.sample", early_kasan_flag_page_alloc_sample); + +/* kasan.page_alloc.sample.order=<minimum page order> */ +static int __init early_kasan_flag_page_alloc_sample_order(char *arg) +{ + int rv; + + if (!arg) + return -EINVAL; + + rv = kstrtouint(arg, 0, &kasan_page_alloc_sample_order); + if (rv) + return rv; + + if (kasan_page_alloc_sample_order > INT_MAX) { + kasan_page_alloc_sample_order = PAGE_ALLOC_SAMPLE_ORDER_DEFAULT; + return -EINVAL; + } + + return 0; +} +early_param("kasan.page_alloc.sample.order", early_kasan_flag_page_alloc_sample_order); + /* * kasan_init_hw_tags_cpu() is called for each CPU. * Not marked as __init as a CPU can be hot-plugged after boot. diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index ea8cf1310b1e..32413f22aa82 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -42,6 +42,10 @@ enum kasan_mode { extern enum kasan_mode kasan_mode __ro_after_init; +extern unsigned long kasan_page_alloc_sample; +extern unsigned int kasan_page_alloc_sample_order; +DECLARE_PER_CPU(long, kasan_page_alloc_skip); + static inline bool kasan_vmalloc_enabled(void) { return static_branch_likely(&kasan_flag_vmalloc); @@ -57,6 +61,24 @@ static inline bool kasan_sync_fault_possible(void) return kasan_mode == KASAN_MODE_SYNC || kasan_mode == KASAN_MODE_ASYMM; } +static inline bool kasan_sample_page_alloc(unsigned int order) +{ + /* Fast-path for when sampling is disabled. */ + if (kasan_page_alloc_sample == 1) + return true; + + if (order < kasan_page_alloc_sample_order) + return true; + + if (this_cpu_dec_return(kasan_page_alloc_skip) < 0) { + this_cpu_write(kasan_page_alloc_skip, + kasan_page_alloc_sample - 1); + return true; + } + + return false; +} + #else /* CONFIG_KASAN_HW_TAGS */ static inline bool kasan_async_fault_possible(void) @@ -69,6 +91,11 @@ static inline bool kasan_sync_fault_possible(void) return true; } +static inline bool kasan_sample_page_alloc(unsigned int order) +{ + return true; +} + #endif /* CONFIG_KASAN_HW_TAGS */ #ifdef CONFIG_KASAN_GENERIC |