kasan: rework krealloc tests

This patch reworks KASAN-KUnit tests for krealloc() to:

1. Check both slab and page_alloc based krealloc() implementations.
2. Allow at least one full granule to fit between old and new sizes for
   each KASAN mode, and check accesses to that granule accordingly.

Link: https://lkml.kernel.org/r/c707f128a2bb9f2f05185d1eb52192cf179cf4fa.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 2557630..e1bd1d1 100644 (file)
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -252,11 +252,14 @@ static void kmalloc_large_oob_right(struct kunit *test)
        kfree(ptr);
 }
 
-static void kmalloc_oob_krealloc_more(struct kunit *test)
+static void krealloc_more_oob_helper(struct kunit *test,
+                                       size_t size1, size_t size2)
 {
        char *ptr1, *ptr2;
-       size_t size1 = 17;
-       size_t size2 = 19;
+       size_t middle;
+
+       KUNIT_ASSERT_LT(test, size1, size2);
+       middle = size1 + (size2 - size1) / 2;
 
        ptr1 = kmalloc(size1, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -264,15 +267,31 @@ static void kmalloc_oob_krealloc_more(struct kunit *test)
        ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
 
-       KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2 + OOB_TAG_OFF] = 'x');
+       /* All offsets up to size2 must be accessible. */
+       ptr2[size1 - 1] = 'x';
+       ptr2[size1] = 'x';
+       ptr2[middle] = 'x';
+       ptr2[size2 - 1] = 'x';
+
+       /* Generic mode is precise, so unaligned size2 must be inaccessible. */
+       if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+               KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');
+
+       /* For all modes first aligned offset after size2 must be inaccessible. */
+       KUNIT_EXPECT_KASAN_FAIL(test,
+               ptr2[round_up(size2, KASAN_GRANULE_SIZE)] = 'x');
+
        kfree(ptr2);
 }
 
-static void kmalloc_oob_krealloc_less(struct kunit *test)
+static void krealloc_less_oob_helper(struct kunit *test,
+                                       size_t size1, size_t size2)
 {
        char *ptr1, *ptr2;
-       size_t size1 = 17;
-       size_t size2 = 15;
+       size_t middle;
+
+       KUNIT_ASSERT_LT(test, size2, size1);
+       middle = size2 + (size1 - size2) / 2;
 
        ptr1 = kmalloc(size1, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
@@ -280,10 +299,60 @@ static void kmalloc_oob_krealloc_less(struct kunit *test)
        ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
 
-       KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2 + OOB_TAG_OFF] = 'x');
+       /* Must be accessible for all modes. */
+       ptr2[size2 - 1] = 'x';
+
+       /* Generic mode is precise, so unaligned size2 must be inaccessible. */
+       if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+               KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size2] = 'x');
+
+       /* For all modes first aligned offset after size2 must be inaccessible. */
+       KUNIT_EXPECT_KASAN_FAIL(test,
+               ptr2[round_up(size2, KASAN_GRANULE_SIZE)] = 'x');
+
+       /*
+        * For all modes all size2, middle, and size1 should land in separate
+        * granules and thus the latter two offsets should be inaccessible.
+        */
+       KUNIT_EXPECT_LE(test, round_up(size2, KASAN_GRANULE_SIZE),
+                               round_down(middle, KASAN_GRANULE_SIZE));
+       KUNIT_EXPECT_LE(test, round_up(middle, KASAN_GRANULE_SIZE),
+                               round_down(size1, KASAN_GRANULE_SIZE));
+       KUNIT_EXPECT_KASAN_FAIL(test, ptr2[middle] = 'x');
+       KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size1 - 1] = 'x');
+       KUNIT_EXPECT_KASAN_FAIL(test, ptr2[size1] = 'x');
+
        kfree(ptr2);
 }
 
+static void krealloc_more_oob(struct kunit *test)
+{
+       krealloc_more_oob_helper(test, 201, 235);
+}
+
+static void krealloc_less_oob(struct kunit *test)
+{
+       krealloc_less_oob_helper(test, 235, 201);
+}
+
+static void krealloc_pagealloc_more_oob(struct kunit *test)
+{
+       /* page_alloc fallback in only implemented for SLUB. */
+       KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB);
+
+       krealloc_more_oob_helper(test, KMALLOC_MAX_CACHE_SIZE + 201,
+                                       KMALLOC_MAX_CACHE_SIZE + 235);
+}
+
+static void krealloc_pagealloc_less_oob(struct kunit *test)
+{
+       /* page_alloc fallback in only implemented for SLUB. */
+       KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB);
+
+       krealloc_less_oob_helper(test, KMALLOC_MAX_CACHE_SIZE + 235,
+                                       KMALLOC_MAX_CACHE_SIZE + 201);
+}
+
 static void kmalloc_oob_16(struct kunit *test)
 {
        struct {
@@ -977,8 +1046,10 @@ static struct kunit_case kasan_kunit_test_cases[] = {
        KUNIT_CASE(pagealloc_oob_right),
        KUNIT_CASE(pagealloc_uaf),
        KUNIT_CASE(kmalloc_large_oob_right),
-       KUNIT_CASE(kmalloc_oob_krealloc_more),
-       KUNIT_CASE(kmalloc_oob_krealloc_less),
+       KUNIT_CASE(krealloc_more_oob),
+       KUNIT_CASE(krealloc_less_oob),
+       KUNIT_CASE(krealloc_pagealloc_more_oob),
+       KUNIT_CASE(krealloc_pagealloc_less_oob),
        KUNIT_CASE(kmalloc_oob_16),
        KUNIT_CASE(kmalloc_uaf_16),
        KUNIT_CASE(kmalloc_oob_in_memset),