On Thu, May 6, 2021 at 11:20 PM Peter Collingbourne <pcc@xxxxxxxxxx> wrote: > > These tests deliberately access these arrays out of bounds, > which will cause the dynamic local bounds checks inserted by > CONFIG_UBSAN_LOCAL_BOUNDS to fail and panic the kernel. To avoid this > problem, access the arrays via volatile pointers, which will prevent > the compiler from being able to determine the array bounds. > > Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Link: https://linux-review.googlesource.com/id/I90b1713fbfa1bf68ff895aef099ea77b98a7c3b9 > --- > lib/test_kasan.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index dc05cfc2d12f..2a078e8e7b8e 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -654,8 +654,8 @@ static char global_array[10]; > > static void kasan_global_oob(struct kunit *test) > { > - volatile int i = 3; > - char *p = &global_array[ARRAY_SIZE(global_array) + i]; > + char *volatile array = global_array; > + char *p = &array[ARRAY_SIZE(global_array) + 3]; Nit: in the kernel, "volatile" usually comes before the pointer type. > > /* Only generic mode instruments globals. */ > KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); > @@ -703,8 +703,8 @@ static void ksize_uaf(struct kunit *test) > static void kasan_stack_oob(struct kunit *test) > { > char stack_array[10]; > - volatile int i = OOB_TAG_OFF; > - char *p = &stack_array[ARRAY_SIZE(stack_array) + i]; > + char *volatile array = stack_array; > + char *p = &array[ARRAY_SIZE(stack_array) + OOB_TAG_OFF]; > > KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_STACK); > > @@ -715,7 +715,8 @@ static void kasan_alloca_oob_left(struct kunit *test) > { > volatile int i = 10; > char alloca_array[i]; > - char *p = alloca_array - 1; > + char *volatile array = alloca_array; > + char *p = array - 1; > > /* Only generic mode instruments dynamic allocas. */ > KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); > @@ -728,7 +729,8 @@ static void kasan_alloca_oob_right(struct kunit *test) > { > volatile int i = 10; > char alloca_array[i]; > - char *p = alloca_array + i; > + char *volatile array = alloca_array; > + char *p = array + i; > > /* Only generic mode instruments dynamic allocas. */ > KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); > -- > 2.31.1.607.g51e8a6a459-goog > Acked-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Thanks, Peter!
