On Tue, Jan 05, 2021 at 07:27PM +0100, Andrey Konovalov wrote: > Add 3 new tests for tag-based KASAN modes: > > 1. Check that match-all pointer tag is not assigned randomly. > 2. Check that 0xff works as a match-all pointer tag. > 3. Check that there are no match-all memory tags. > > Note, that test #3 causes a significant number (255) of KASAN reports > to be printed during execution for the SW_TAGS mode. > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > Link: https://linux-review.googlesource.com/id/I78f1375efafa162b37f3abcb2c5bc2f3955dfd8e > --- > lib/test_kasan.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++ > mm/kasan/kasan.h | 6 ++++ > 2 files changed, 99 insertions(+) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index 46e578c8e842..f1eda0bcc780 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -13,6 +13,7 @@ > #include <linux/mman.h> > #include <linux/module.h> > #include <linux/printk.h> > +#include <linux/random.h> > #include <linux/slab.h> > #include <linux/string.h> > #include <linux/uaccess.h> > @@ -790,6 +791,95 @@ static void vmalloc_oob(struct kunit *test) > vfree(area); > } > > +/* > + * Check that match-all pointer tag is not assigned randomly for > + * tag-based modes. > + */ > +static void match_all_not_assigned(struct kunit *test) > +{ > + char *ptr; > + struct page *pages; > + int i, size, order; > + > + for (i = 0; i < 256; i++) { > + size = get_random_int() % KMALLOC_MAX_SIZE; size appears to be unused? > + ptr = kmalloc(128, GFP_KERNEL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > + KUNIT_EXPECT_NE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); > + kfree(ptr); > + } > + > + for (i = 0; i < 256; i++) { > + order = get_random_int() % 4; > + pages = alloc_pages(GFP_KERNEL, order); > + ptr = page_address(pages); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > + KUNIT_EXPECT_NE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); > + free_pages((unsigned long)ptr, order); > + } > +} > + > +/* Check that 0xff works as a match-all pointer tag for tag-based modes. */ > +static void match_all_ptr_tag(struct kunit *test) > +{ > + char *ptr; > + u8 tag; > + > + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > + return; > + } > + > + ptr = kmalloc(128, GFP_KERNEL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > + > + /* Backup the assigned tag. */ > + tag = get_tag(ptr); > + KUNIT_EXPECT_NE(test, tag, (u8)KASAN_TAG_KERNEL); > + > + /* Reset the tag to 0xff.*/ > + ptr = set_tag(ptr, KASAN_TAG_KERNEL); > + > + /* This access shouldn't trigger a KASAN report. */ > + *ptr = 0; > + > + /* Recover the pointer tag and free. */ > + ptr = set_tag(ptr, tag); > + kfree(ptr); > +} > + > +/* Check that there are no match-all memory tags for tag-based modes. */ > +static void match_all_mem_tag(struct kunit *test) > +{ > + char *ptr; > + int tag; > + > + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { > + kunit_info(test, "skipping, CONFIG_KASAN_SW/HW_TAGS required"); > + return; > + } > + > + ptr = kmalloc(128, GFP_KERNEL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > + KUNIT_EXPECT_NE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL); > + > + /* For each possible tag value not matching the pointer tag. */ > + for (tag = KASAN_TAG_MIN; tag <= KASAN_TAG_KERNEL; tag++) { > + if (tag == get_tag(ptr)) > + continue; > + > + /* Mark the first memory granule with the chosen memory tag. */ > + kasan_poison(ptr, KASAN_GRANULE_SIZE, (u8)tag); > + > + /* This access must cause a KASAN report. */ > + KUNIT_EXPECT_KASAN_FAIL(test, *ptr = 0); > + } > + > + /* Recover the memory tag and free. */ > + kasan_poison(ptr, KASAN_GRANULE_SIZE, get_tag(ptr)); > + kfree(ptr); > +} > + > static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(kmalloc_oob_right), > KUNIT_CASE(kmalloc_oob_left), > @@ -829,6 +919,9 @@ static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(kasan_bitops_tags), > KUNIT_CASE(kmalloc_double_kzfree), > KUNIT_CASE(vmalloc_oob), > + KUNIT_CASE(match_all_not_assigned), > + KUNIT_CASE(match_all_ptr_tag), > + KUNIT_CASE(match_all_mem_tag), > {} > }; > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 3b38baddec47..c3fb9bf241d3 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -36,6 +36,12 @@ extern bool kasan_flag_panic __ro_after_init; > #define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */ > #define KASAN_TAG_MAX 0xFD /* maximum value for random tags */ > > +#ifdef CONFIG_KASAN_HW_TAGS > +#define KASAN_TAG_MIN 0xF0 /* mimimum value for random tags */ > +#else > +#define KASAN_TAG_MIN 0x00 /* mimimum value for random tags */ > +#endif > + > #ifdef CONFIG_KASAN_GENERIC > #define KASAN_FREE_PAGE 0xFF /* page was freed */ > #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */ > -- > 2.29.2.729.g45daf8777d-goog >
