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.ryabi...@samsung.com>
---
include/linux/kasan.h | 7 +++++++
mm/compaction.c | 2 ++
mm/kasan/kasan.c | 14 ++++++++++++++
mm/kasan/report.c | 11 +++++++++++
mm/page_alloc.c | 3 +++
5 files changed, 37 insertions(+)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 063a3f3..a278ccc 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -11,6 +11,7 @@ struct page;
#define KASAN_SHADOW_SCALE_SHIFT 3
#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
+#define KASAN_FREE_PAGE 0xFF /* page was freed */
#define KASAN_SHADOW_GAP 0xF9 /* address belongs to shadow memory */
#include <asm/kasan.h>
@@ -33,6 +34,9 @@ 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) {}
@@ -40,6 +44,9 @@ 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 546e571..12f2c7d 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
@@ -61,6 +62,7 @@ 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 740d5b2..efe8105 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -247,6 +247,20 @@ static __always_inline void check_memory_region(unsigned
long addr,
kasan_report(addr, size, write);
}
+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);
+}
+
#define DECLARE_ASAN_CHECK(size) \
void __asan_load##size(unsigned long addr) \
{ \
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 62b942a..7983ebb 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -54,6 +54,9 @@ static void print_error_description(struct access_info *info)
shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);
switch (shadow_val) {
+ case KASAN_FREE_PAGE:
+ bug_type = "use after free";
+ break;
case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
bug_type = "out of bounds access";
break;
@@ -72,6 +75,14 @@ static void print_error_description(struct access_info *info)
static void print_address_description(struct access_info *info)
{
+ unsigned long addr = info->access_addr;
+
+ if ((addr >= PAGE_OFFSET) &&
+ (addr < (unsigned long)high_memory)) {
+ struct page *page = virt_to_head_page((void *)addr);
+ dump_page(page, "kasan: bad access detected");
+ }
+
dump_stack();
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7633c50..3a75171 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -25,6 +25,7 @@
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kmemcheck.h>
+#include <linux/kasan.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
@@ -807,6 +808,7 @@ 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;
@@ -985,6 +987,7 @@ 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);
--
2.2.1
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