linux/lib/test_ubsan.c
Andrey Ryabinin 6aaa31aeb9 ubsan: remove overflow checks
Since GCC 8.0 -fsanitize=signed-integer-overflow doesn't work with
-fwrapv.  -fwrapv makes signed overflows defines and GCC essentially
disables ubsan checks.  On GCC < 8.0 -fwrapv doesn't have influence on
-fsanitize=signed-integer-overflow setting, so it kinda works but
generates false-positves and violates uaccess rules:

lib/iov_iter.o: warning: objtool: iovec_from_user()+0x22d: call to
__ubsan_handle_add_overflow() with UACCESS enabled

Disable signed overflow checks to avoid these problems.  Remove unsigned
overflow checks as well.  Unsigned overflow appeared as side effect of
commit cdf8a76fda ("ubsan: move cc-option tests into Kconfig"), but it
never worked (kernel doesn't boot).  And unsigned overflows are allowed by
C standard, so it just pointless.

Link: https://lkml.kernel.org/r/20210209232348.20510-1-ryabinin.a.a@gmail.com
Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-26 09:41:05 -08:00

145 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
typedef void(*test_ubsan_fp)(void);
#define UBSAN_TEST(config, ...) do { \
pr_info("%s " __VA_ARGS__ "%s(%s=%s)\n", __func__, \
sizeof(" " __VA_ARGS__) > 2 ? " " : "", \
#config, IS_ENABLED(config) ? "y" : "n"); \
} while (0)
static void test_ubsan_divrem_overflow(void)
{
volatile int val = 16;
volatile int val2 = 0;
UBSAN_TEST(CONFIG_UBSAN_DIV_ZERO);
val /= val2;
}
static void test_ubsan_shift_out_of_bounds(void)
{
volatile int neg = -1, wrap = 4;
int val1 = 10;
int val2 = INT_MAX;
UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
val1 <<= neg;
UBSAN_TEST(CONFIG_UBSAN_SHIFT, "left overflow");
val2 <<= wrap;
}
static void test_ubsan_out_of_bounds(void)
{
volatile int i = 4, j = 5, k = -1;
volatile char above[4] = { }; /* Protect surrounding memory. */
volatile int arr[4];
volatile char below[4] = { }; /* Protect surrounding memory. */
above[0] = below[0];
UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "above");
arr[j] = i;
UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "below");
arr[k] = i;
}
enum ubsan_test_enum {
UBSAN_TEST_ZERO = 0,
UBSAN_TEST_ONE,
UBSAN_TEST_MAX,
};
static void test_ubsan_load_invalid_value(void)
{
volatile char *dst, *src;
bool val, val2, *ptr;
enum ubsan_test_enum eval, eval2, *eptr;
unsigned char c = 0xff;
UBSAN_TEST(CONFIG_UBSAN_BOOL, "bool");
dst = (char *)&val;
src = &c;
*dst = *src;
ptr = &val2;
val2 = val;
UBSAN_TEST(CONFIG_UBSAN_ENUM, "enum");
dst = (char *)&eval;
src = &c;
*dst = *src;
eptr = &eval2;
eval2 = eval;
}
static void test_ubsan_null_ptr_deref(void)
{
volatile int *ptr = NULL;
int val;
UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
val = *ptr;
}
static void test_ubsan_misaligned_access(void)
{
volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
volatile int *ptr, val = 6;
UBSAN_TEST(CONFIG_UBSAN_ALIGNMENT);
ptr = (int *)(arr + 1);
*ptr = val;
}
static void test_ubsan_object_size_mismatch(void)
{
/* "((aligned(8)))" helps this not into be misaligned for ptr-access. */
volatile int val __aligned(8) = 4;
volatile long long *ptr, val2;
UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
ptr = (long long *)&val;
val2 = *ptr;
}
static const test_ubsan_fp test_ubsan_array[] = {
test_ubsan_shift_out_of_bounds,
test_ubsan_out_of_bounds,
test_ubsan_load_invalid_value,
test_ubsan_misaligned_access,
test_ubsan_object_size_mismatch,
};
/* Excluded because they Oops the module. */
static const test_ubsan_fp skip_ubsan_array[] = {
test_ubsan_divrem_overflow,
test_ubsan_null_ptr_deref,
};
static int __init test_ubsan_init(void)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(test_ubsan_array); i++)
test_ubsan_array[i]();
return 0;
}
module_init(test_ubsan_init);
static void __exit test_ubsan_exit(void)
{
/* do nothing */
}
module_exit(test_ubsan_exit);
MODULE_AUTHOR("Jinbum Park <jinb.park7@gmail.com>");
MODULE_LICENSE("GPL v2");