Add kernel address sanitizer hooks to mark allocated page's addresses as accessible in corresponding shadow region. Mark freed pages as inaccessible. Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> --- include/linux/kasan.h | 6 ++++++ mm/compaction.c | 2 ++ mm/kasan/kasan.c | 14 ++++++++++++++ mm/kasan/kasan.h | 1 + mm/kasan/report.c | 7 +++++++ mm/page_alloc.c | 3 +++ 6 files changed, 33 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 01c99fe..9714fba 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -30,6 +30,9 @@ static inline void kasan_disable_local(void) void kasan_unpoison_shadow(const void *address, size_t size); +void kasan_alloc_pages(struct page *page, unsigned int order); +void kasan_free_pages(struct page *page, unsigned int order); + #else /* CONFIG_KASAN */ static inline void kasan_unpoison_shadow(const void *address, size_t size) {} @@ -37,6 +40,9 @@ static inline void kasan_unpoison_shadow(const void *address, size_t size) {} static inline void kasan_enable_local(void) {} static inline void kasan_disable_local(void) {} +static inline void kasan_alloc_pages(struct page *page, unsigned int order) {} +static inline void kasan_free_pages(struct page *page, unsigned int order) {} + #endif /* CONFIG_KASAN */ #endif /* LINUX_KASAN_H */ diff --git a/mm/compaction.c b/mm/compaction.c index edba18a..834f846 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -16,6 +16,7 @@ #include <linux/sysfs.h> #include <linux/balloon_compaction.h> #include <linux/page-isolation.h> +#include <linux/kasan.h> #include "internal.h" #ifdef CONFIG_COMPACTION @@ -59,6 +60,7 @@ static void map_pages(struct list_head *list) list_for_each_entry(page, list, lru) { arch_alloc_page(page, 0); kernel_map_pages(page, 1, 1); + kasan_alloc_pages(page, 0); } } diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 8ce738e..5782082 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -259,6 +259,20 @@ static __always_inline void check_memory_region(unsigned long addr, kasan_report_error(&info); } +void kasan_alloc_pages(struct page *page, unsigned int order) +{ + if (likely(!PageHighMem(page))) + kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); +} + +void kasan_free_pages(struct page *page, unsigned int order) +{ + if (likely(!PageHighMem(page))) + kasan_poison_shadow(page_address(page), + PAGE_SIZE << order, + KASAN_FREE_PAGE); +} + void __asan_load1(unsigned long addr) { check_memory_region(addr, 1, false); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 9a9fe9f..ee572c4 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -6,6 +6,7 @@ #define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT) #define KASAN_SHADOW_MASK (KASAN_SHADOW_SCALE_SIZE - 1) +#define KASAN_FREE_PAGE 0xFF /* page was freed */ #define KASAN_SHADOW_GAP 0xF9 /* address belongs to shadow memory */ struct access_info { diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 89a9aa1..707323b 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -57,6 +57,9 @@ static void print_error_description(struct access_info *info) case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: bug_type = "out of bounds access"; break; + case KASAN_FREE_PAGE: + bug_type = "use after free"; + break; case KASAN_SHADOW_GAP: bug_type = "wild memory access"; break; @@ -75,6 +78,10 @@ static void print_address_description(struct access_info *info) page = virt_to_head_page((void *)info->access_addr); switch (shadow_val) { + case KASAN_FREE_PAGE: + dump_page(page, "kasan error"); + dump_stack(); + break; case KASAN_SHADOW_GAP: pr_err("No metainfo is available for this access.\n"); dump_stack(); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 53e10ff..88b5032 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -59,6 +59,7 @@ #include <linux/page-debug-flags.h> #include <linux/hugetlb.h> #include <linux/sched/rt.h> +#include <linux/kasan.h> #include <asm/sections.h> #include <asm/tlbflush.h> @@ -755,6 +756,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order) trace_mm_page_free(page, order); kmemcheck_free_shadow(page, order); + kasan_free_pages(page, order); if (PageAnon(page)) page->mapping = NULL; @@ -941,6 +943,7 @@ 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); + kasan_alloc_pages(page, order); if (gfp_flags & __GFP_ZERO) prep_zero_page(page, order, gfp_flags); -- 2.1.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>