From 9cf016e6b49b53d6c15d4137c034178148149ef4 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 6 Apr 2020 20:10:12 -0700 Subject: [PATCH] lib: test_stackinit.c: XFAIL switch variable init tests The tests for initializing a variable defined between a switch statement's test and its first "case" statement are currently not initialized in Clang[1] nor the proposed auto-initialization feature in GCC. We should retain the test (so that we can evaluate compiler fixes), but mark it as an "expected fail". The rest of the kernel source will be adjusted to avoid this corner case. Also disable -Wswitch-unreachable for the test so that the intentionally broken code won't trigger warnings for GCC (nor future Clang) when initialization happens this unhandled place. [1] https://bugs.llvm.org/show_bug.cgi?id=44916 Suggested-by: Alexander Potapenko Signed-off-by: Kees Cook Signed-off-by: Andrew Morton Cc: Jann Horn Cc: Ard Biesheuvel Link: http://lkml.kernel.org/r/202002191358.2897A07C6@keescook Signed-off-by: Linus Torvalds --- lib/Makefile | 1 + lib/test_stackinit.c | 28 ++++++++++++++++++---------- 2 files changed, 19 insertions(+), 10 deletions(-) diff --git a/lib/Makefile b/lib/Makefile index 0fd125c4ad07..93d05ff4f501 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -87,6 +87,7 @@ obj-$(CONFIG_TEST_KMOD) += test_kmod.o obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o +CFLAGS_test_stackinit.o += $(call cc-disable-warning, switch-unreachable) obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o diff --git a/lib/test_stackinit.c b/lib/test_stackinit.c index 2d7d257a430e..f93b1e145ada 100644 --- a/lib/test_stackinit.c +++ b/lib/test_stackinit.c @@ -92,8 +92,9 @@ static bool range_contains(char *haystack_start, size_t haystack_size, * @var_type: type to be tested for zeroing initialization * @which: is this a SCALAR, STRING, or STRUCT type? * @init_level: what kind of initialization is performed + * @xfail: is this test expected to fail? */ -#define DEFINE_TEST_DRIVER(name, var_type, which) \ +#define DEFINE_TEST_DRIVER(name, var_type, which, xfail) \ /* Returns 0 on success, 1 on failure. */ \ static noinline __init int test_ ## name (void) \ { \ @@ -139,13 +140,14 @@ static noinline __init int test_ ## name (void) \ for (sum = 0, i = 0; i < target_size; i++) \ sum += (check_buf[i] == 0xFF); \ \ - if (sum == 0) \ + if (sum == 0) { \ pr_info(#name " ok\n"); \ - else \ - pr_warn(#name " FAIL (uninit bytes: %d)\n", \ - sum); \ - \ - return (sum != 0); \ + return 0; \ + } else { \ + pr_warn(#name " %sFAIL (uninit bytes: %d)\n", \ + (xfail) ? "X" : "", sum); \ + return (xfail) ? 0 : 1; \ + } \ } #define DEFINE_TEST(name, var_type, which, init_level) \ /* no-op to force compiler into ignoring "uninitialized" vars */\ @@ -189,7 +191,7 @@ static noinline __init int leaf_ ## name(unsigned long sp, \ \ return (int)buf[0] | (int)buf[sizeof(buf) - 1]; \ } \ -DEFINE_TEST_DRIVER(name, var_type, which) +DEFINE_TEST_DRIVER(name, var_type, which, 0) /* Structure with no padding. */ struct test_packed { @@ -326,8 +328,14 @@ static noinline __init int leaf_switch_2_none(unsigned long sp, bool fill, return __leaf_switch_none(2, fill); } -DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR); -DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR); +/* + * These are expected to fail for most configurations because neither + * GCC nor Clang have a way to perform initialization of variables in + * non-code areas (i.e. in a switch statement before the first "case"). + * https://bugs.llvm.org/show_bug.cgi?id=44916 + */ +DEFINE_TEST_DRIVER(switch_1_none, uint64_t, SCALAR, 1); +DEFINE_TEST_DRIVER(switch_2_none, uint64_t, SCALAR, 1); static int __init test_stackinit_init(void) {