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authorKees Cook <keescook@chromium.org>2020-04-06 20:10:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:43 -0700
commit9cf016e6b49b53d6c15d4137c034178148149ef4 (patch)
treec5c273b273083738e8941b83cbf217f3e6a8a0a3
parent6e85318521c001b6af82830774a8a7d05eec6adf (diff)
downloadlinux-9cf016e6b49b53d6c15d4137c034178148149ef4.tar.bz2
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 <glider@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jann Horn <jannh@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: http://lkml.kernel.org/r/202002191358.2897A07C6@keescook Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--lib/Makefile1
-rw-r--r--lib/test_stackinit.c28
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)
{