Re: [PATCH 08/11] kasan: adopt kmalloc_uaf2 test to HW_TAGS mode

On Tue, Jan 12, 2021 at 9:26 AM Alexander Potapenko [off-list ref] wrote:

Nit: s/adopt/adapt in the title.

quoted

+again:
        ptr1 = kmalloc(size, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);

@@ -384,6 +386,13 @@ static void kmalloc_uaf2(struct kunit *test)
        ptr2 = kmalloc(size, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);

+       /*
+        * For tag-based KASAN ptr1 and ptr2 tags might happen to be the same.
+        * Allow up to 4 attempts at generating different tags.
+        */
+       if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 4)
+               goto again;
+

Looks like we are leaking memory allocated for ptr2 here?

Will fix in v2, thanks!