lib/test_kasan.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
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(+)
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]);
--
2.32.0On 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.
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