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6aaa31aeb9
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>
145 lines
2.9 KiB
C
145 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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typedef void(*test_ubsan_fp)(void);
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#define UBSAN_TEST(config, ...) do { \
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pr_info("%s " __VA_ARGS__ "%s(%s=%s)\n", __func__, \
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sizeof(" " __VA_ARGS__) > 2 ? " " : "", \
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#config, IS_ENABLED(config) ? "y" : "n"); \
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} while (0)
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static void test_ubsan_divrem_overflow(void)
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{
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volatile int val = 16;
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volatile int val2 = 0;
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UBSAN_TEST(CONFIG_UBSAN_DIV_ZERO);
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val /= val2;
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}
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static void test_ubsan_shift_out_of_bounds(void)
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{
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volatile int neg = -1, wrap = 4;
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int val1 = 10;
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int val2 = INT_MAX;
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UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
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val1 <<= neg;
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UBSAN_TEST(CONFIG_UBSAN_SHIFT, "left overflow");
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val2 <<= wrap;
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}
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static void test_ubsan_out_of_bounds(void)
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{
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volatile int i = 4, j = 5, k = -1;
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volatile char above[4] = { }; /* Protect surrounding memory. */
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volatile int arr[4];
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volatile char below[4] = { }; /* Protect surrounding memory. */
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above[0] = below[0];
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UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "above");
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arr[j] = i;
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UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "below");
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arr[k] = i;
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}
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enum ubsan_test_enum {
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UBSAN_TEST_ZERO = 0,
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UBSAN_TEST_ONE,
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UBSAN_TEST_MAX,
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};
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static void test_ubsan_load_invalid_value(void)
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{
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volatile char *dst, *src;
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bool val, val2, *ptr;
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enum ubsan_test_enum eval, eval2, *eptr;
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unsigned char c = 0xff;
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UBSAN_TEST(CONFIG_UBSAN_BOOL, "bool");
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dst = (char *)&val;
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src = &c;
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*dst = *src;
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ptr = &val2;
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val2 = val;
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UBSAN_TEST(CONFIG_UBSAN_ENUM, "enum");
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dst = (char *)&eval;
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src = &c;
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*dst = *src;
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eptr = &eval2;
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eval2 = eval;
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}
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static void test_ubsan_null_ptr_deref(void)
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{
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volatile int *ptr = NULL;
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int val;
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UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
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val = *ptr;
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}
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static void test_ubsan_misaligned_access(void)
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{
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volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
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volatile int *ptr, val = 6;
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UBSAN_TEST(CONFIG_UBSAN_ALIGNMENT);
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ptr = (int *)(arr + 1);
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*ptr = val;
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}
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static void test_ubsan_object_size_mismatch(void)
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{
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/* "((aligned(8)))" helps this not into be misaligned for ptr-access. */
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volatile int val __aligned(8) = 4;
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volatile long long *ptr, val2;
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UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
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ptr = (long long *)&val;
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val2 = *ptr;
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}
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static const test_ubsan_fp test_ubsan_array[] = {
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test_ubsan_shift_out_of_bounds,
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test_ubsan_out_of_bounds,
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test_ubsan_load_invalid_value,
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test_ubsan_misaligned_access,
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test_ubsan_object_size_mismatch,
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};
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/* Excluded because they Oops the module. */
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static const test_ubsan_fp skip_ubsan_array[] = {
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test_ubsan_divrem_overflow,
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test_ubsan_null_ptr_deref,
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};
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static int __init test_ubsan_init(void)
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{
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(test_ubsan_array); i++)
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test_ubsan_array[i]();
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return 0;
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}
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module_init(test_ubsan_init);
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static void __exit test_ubsan_exit(void)
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{
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/* do nothing */
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}
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module_exit(test_ubsan_exit);
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MODULE_AUTHOR("Jinbum Park <jinb.park7@gmail.com>");
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MODULE_LICENSE("GPL v2");
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