| Message ID | 20220608214024.1068451-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | aaf50b1969d7933a51ea421b11432a7fb90974e3 |
| Headers | show |
| Series | kasan: test: Silence GCC 12 warnings | expand |
On Wed, 8 Jun 2022 at 23:40, Kees Cook <keescook@chromium.org> wrote: > > GCC 12 continues to get smarter about array accesses. The KASAN tests > are expecting to explicitly test out-of-bounds conditions at run-time, > so hide the variable from GCC, to avoid warnings like: > > ../lib/test_kasan.c: In function 'ksize_uaf': > ../lib/test_kasan.c:790:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds] Since this keeps happening, I wonder if we could just pass '-Wno-array-bounds' ? We already have 'CFLAGS_test_kasan.o += $(call cc-disable-warning, vla)'. Although eventually I'd assume all the OPTIMIZE_HIDE_VAR() should be in place, and hopefully it'll have been the last one. I leave it to you. > 790 | KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]); > | ~~~~~~~~~~~~~~~~~~~~~~^~~~~~ > ../lib/test_kasan.c:97:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL' > 97 | expression; \ > | ^~~~~~~~~~ > > Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> > Cc: kasan-dev@googlegroups.com > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > lib/test_kasan.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index c233b1a4e984..58c1b01ccfe2 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -131,6 +131,7 @@ static void kmalloc_oob_right(struct kunit *test) > ptr = kmalloc(size, GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > /* > * An unaligned access past the requested kmalloc size. > * Only generic KASAN can precisely detect these. > @@ -159,6 +160,7 @@ static void kmalloc_oob_left(struct kunit *test) > ptr = kmalloc(size, GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > KUNIT_EXPECT_KASAN_FAIL(test, *ptr = *(ptr - 1)); > kfree(ptr); > } > @@ -171,6 +173,7 @@ static void kmalloc_node_oob_right(struct kunit *test) > ptr = kmalloc_node(size, GFP_KERNEL, 0); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = ptr[size]); > kfree(ptr); > } > @@ -191,6 +194,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test) > ptr = kmalloc(size, GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0); > > kfree(ptr); > @@ -271,6 +275,7 @@ static void kmalloc_large_oob_right(struct kunit *test) > ptr = kmalloc(size, GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0); > kfree(ptr); > } > @@ -410,6 +415,8 @@ static void kmalloc_oob_16(struct kunit *test) > ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL); > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2); > > + OPTIMIZER_HIDE_VAR(ptr1); > + OPTIMIZER_HIDE_VAR(ptr2); > KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2); > kfree(ptr1); > kfree(ptr2); > @@ -756,6 +763,8 @@ static void ksize_unpoisons_memory(struct kunit *test) > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > real_size = ksize(ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > + > /* This access shouldn't trigger a KASAN report. */ > ptr[size] = 'x'; > > @@ -778,6 +787,7 @@ static void ksize_uaf(struct kunit *test) > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > kfree(ptr); > > + OPTIMIZER_HIDE_VAR(ptr); > KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr)); > KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]); > KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]); > -- > 2.32.0 > > -- > 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@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20220608214024.1068451-1-keescook%40chromium.org.
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index c233b1a4e984..58c1b01ccfe2 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -131,6 +131,7 @@ static void kmalloc_oob_right(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); /* * An unaligned access past the requested kmalloc size. * Only generic KASAN can precisely detect these. @@ -159,6 +160,7 @@ static void kmalloc_oob_left(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); KUNIT_EXPECT_KASAN_FAIL(test, *ptr = *(ptr - 1)); kfree(ptr); } @@ -171,6 +173,7 @@ static void kmalloc_node_oob_right(struct kunit *test) ptr = kmalloc_node(size, GFP_KERNEL, 0); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = ptr[size]); kfree(ptr); } @@ -191,6 +194,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0); kfree(ptr); @@ -271,6 +275,7 @@ static void kmalloc_large_oob_right(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + OPTIMIZER_HIDE_VAR(ptr); KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0); kfree(ptr); } @@ -410,6 +415,8 @@ static void kmalloc_oob_16(struct kunit *test) ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2); + OPTIMIZER_HIDE_VAR(ptr1); + OPTIMIZER_HIDE_VAR(ptr2); KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2); kfree(ptr1); kfree(ptr2); @@ -756,6 +763,8 @@ static void ksize_unpoisons_memory(struct kunit *test) KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); real_size = ksize(ptr); + OPTIMIZER_HIDE_VAR(ptr); + /* This access shouldn't trigger a KASAN report. */ ptr[size] = 'x'; @@ -778,6 +787,7 @@ static void ksize_uaf(struct kunit *test) KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); kfree(ptr); + OPTIMIZER_HIDE_VAR(ptr); KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr)); KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[0]); KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]);
GCC 12 continues to get smarter about array accesses. The KASAN tests are expecting to explicitly test out-of-bounds conditions at run-time, so hide the variable from GCC, to avoid warnings like: ../lib/test_kasan.c: In function 'ksize_uaf': ../lib/test_kasan.c:790:61: warning: array subscript 120 is outside array bounds of 'void[120]' [-Warray-bounds] 790 | KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[size]); | ~~~~~~~~~~~~~~~~~~~~~~^~~~~~ ../lib/test_kasan.c:97:9: note: in definition of macro 'KUNIT_EXPECT_KASAN_FAIL' 97 | expression; \ | ^~~~~~~~~~ Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: kasan-dev@googlegroups.com Signed-off-by: Kees Cook <keescook@chromium.org> --- lib/test_kasan.c | 10 ++++++++++ 1 file changed, 10 insertions(+)