On Tue, Apr 21, 2020 at 3:40 AM Walter Wu <walter-zh.wu@xxxxxxxxxxxx> wrote: > > When we use tag-based KASAN, then KASAN unit tests don't detect > out-of-bounds memory access. Because with tag-based KASAN the state > of each 16 aligned bytes of memory is encoded in one shadow byte > and the shadow value is tag of pointer, so we need to read next > shadow byte, the shadow value is not equal to tag of pointer, > then tag-based KASAN will detect out-of-bounds memory access. > > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Alexander Potapenko <glider@xxxxxxxxxx> > Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx> > Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > lib/test_kasan.c | 62 ++++++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 55 insertions(+), 7 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index e3087d90e00d..a164f6b47fe5 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -40,7 +40,12 @@ static noinline void __init kmalloc_oob_right(void) > return; > } Hi Walter, This would be great to have! But I am concerned about these series that port KASAN tests to KUNIT: https://lkml.org/lkml/2020/4/17/1144 I suspect it will be one large merge conflict. Not sure what is the proper way to resovle this. I've added authors to CC. > +#ifdef CONFIG_KASAN_GENERIC > ptr[size] = 'x'; > +#else > + ptr[size + 5] = 'x'; > +#endif > + For this particular snippet I think we can reduce amount of idef'ery and amount of non-compiled code in each configuration with something like: ptr[size + 5] = 'x'; if (ENABLED(CONFIG_KASAN_GENERIC)) ptr[size] = 'x'; One check runs always (it should pass in both configs, right?). The only only in GENERIC, but it's C-level if rather than preprocessor. KUNIT should make 2 bugs per test easily expressable (and testable). > kfree(ptr); > } > > @@ -92,7 +97,12 @@ static noinline void __init kmalloc_pagealloc_oob_right(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > ptr[size] = 0; > +#else > + ptr[size + 6] = 0; > +#endif > + > kfree(ptr); > } > > @@ -162,7 +172,11 @@ static noinline void __init kmalloc_oob_krealloc_more(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > ptr2[size2] = 'x'; > +#else > + ptr2[size2 + 13] = 'x'; > +#endif > kfree(ptr2); > } > > @@ -180,7 +194,12 @@ static noinline void __init kmalloc_oob_krealloc_less(void) > kfree(ptr1); > return; > } > + > +#ifdef CONFIG_KASAN_GENERIC > ptr2[size2] = 'x'; > +#else > + ptr2[size2 + 2] = 'x'; > +#endif > kfree(ptr2); > } > > @@ -216,7 +235,11 @@ static noinline void __init kmalloc_oob_memset_2(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > memset(ptr+7, 0, 2); > +#else > + memset(ptr+15, 0, 2); > +#endif > kfree(ptr); > } > > @@ -232,7 +255,11 @@ static noinline void __init kmalloc_oob_memset_4(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > memset(ptr+5, 0, 4); > +#else > + memset(ptr+15, 0, 4); > +#endif > kfree(ptr); > } > > @@ -249,7 +276,11 @@ static noinline void __init kmalloc_oob_memset_8(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > memset(ptr+1, 0, 8); > +#else > + memset(ptr+15, 0, 8); > +#endif > kfree(ptr); > } > > @@ -265,7 +296,11 @@ static noinline void __init kmalloc_oob_memset_16(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > memset(ptr+1, 0, 16); > +#else > + memset(ptr+15, 0, 16); > +#endif > kfree(ptr); > } > > @@ -281,7 +316,11 @@ static noinline void __init kmalloc_oob_in_memset(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > memset(ptr, 0, size+5); > +#else > + memset(ptr, 0, size+7); > +#endif > kfree(ptr); > } > > @@ -415,7 +454,11 @@ static noinline void __init kmem_cache_oob(void) > return; > } > > +#ifdef CONFIG_KASAN_GENERIC > *p = p[size]; > +#else > + *p = p[size + 8]; > +#endif > kmem_cache_free(cache, p); > kmem_cache_destroy(cache); > } > @@ -497,6 +540,11 @@ static noinline void __init copy_user_test(void) > char __user *usermem; > size_t size = 10; > int unused; > +#ifdef CONFIG_KASAN_GENERIC > + size_t oob_size = 1; > +#else > + size_t oob_size = 7; > +#endif > > kmem = kmalloc(size, GFP_KERNEL); > if (!kmem) > @@ -512,25 +560,25 @@ static noinline void __init copy_user_test(void) > } > > pr_info("out-of-bounds in copy_from_user()\n"); > - unused = copy_from_user(kmem, usermem, size + 1); > + unused = copy_from_user(kmem, usermem, size + oob_size); > > pr_info("out-of-bounds in copy_to_user()\n"); > - unused = copy_to_user(usermem, kmem, size + 1); > + unused = copy_to_user(usermem, kmem, size + oob_size); > > pr_info("out-of-bounds in __copy_from_user()\n"); > - unused = __copy_from_user(kmem, usermem, size + 1); > + unused = __copy_from_user(kmem, usermem, size + oob_size); > > pr_info("out-of-bounds in __copy_to_user()\n"); > - unused = __copy_to_user(usermem, kmem, size + 1); > + unused = __copy_to_user(usermem, kmem, size + oob_size); > > pr_info("out-of-bounds in __copy_from_user_inatomic()\n"); > - unused = __copy_from_user_inatomic(kmem, usermem, size + 1); > + unused = __copy_from_user_inatomic(kmem, usermem, size + oob_size); > > pr_info("out-of-bounds in __copy_to_user_inatomic()\n"); > - unused = __copy_to_user_inatomic(usermem, kmem, size + 1); > + unused = __copy_to_user_inatomic(usermem, kmem, size + oob_size); > > pr_info("out-of-bounds in strncpy_from_user()\n"); > - unused = strncpy_from_user(kmem, usermem, size + 1); > + unused = strncpy_from_user(kmem, usermem, size + oob_size); > > vm_munmap((unsigned long)usermem, PAGE_SIZE); > kfree(kmem); > -- > 2.18.0 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20200421014007.6012-1-walter-zh.wu%40mediatek.com.
