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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>
This commit is contained in:
parent
d54ce6158e
commit
6aaa31aeb9
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@ -112,23 +112,6 @@ config UBSAN_UNREACHABLE
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This option enables -fsanitize=unreachable which checks for control
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flow reaching an expected-to-be-unreachable position.
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config UBSAN_SIGNED_OVERFLOW
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bool "Perform checking for signed arithmetic overflow"
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default UBSAN
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depends on $(cc-option,-fsanitize=signed-integer-overflow)
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help
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This option enables -fsanitize=signed-integer-overflow which checks
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for overflow of any arithmetic operations with signed integers.
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config UBSAN_UNSIGNED_OVERFLOW
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bool "Perform checking for unsigned arithmetic overflow"
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depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
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depends on !X86_32 # avoid excessive stack usage on x86-32/clang
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help
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This option enables -fsanitize=unsigned-integer-overflow which checks
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for overflow of any arithmetic operations with unsigned integers. This
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currently causes x86 to fail to boot.
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config UBSAN_OBJECT_SIZE
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bool "Perform checking for accesses beyond the end of objects"
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default UBSAN
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@ -11,51 +11,6 @@ typedef void(*test_ubsan_fp)(void);
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#config, IS_ENABLED(config) ? "y" : "n"); \
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} while (0)
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static void test_ubsan_add_overflow(void)
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{
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volatile int val = INT_MAX;
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volatile unsigned int uval = UINT_MAX;
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UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
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val += 2;
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UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
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uval += 2;
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}
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static void test_ubsan_sub_overflow(void)
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{
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volatile int val = INT_MIN;
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volatile unsigned int uval = 0;
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volatile int val2 = 2;
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UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
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val -= val2;
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UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
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uval -= val2;
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}
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static void test_ubsan_mul_overflow(void)
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{
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volatile int val = INT_MAX / 2;
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volatile unsigned int uval = UINT_MAX / 2;
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UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
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val *= 3;
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UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
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uval *= 3;
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}
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static void test_ubsan_negate_overflow(void)
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{
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volatile int val = INT_MIN;
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UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
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val = -val;
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}
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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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@ -155,10 +110,6 @@ static void test_ubsan_object_size_mismatch(void)
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}
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static const test_ubsan_fp test_ubsan_array[] = {
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test_ubsan_add_overflow,
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test_ubsan_sub_overflow,
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test_ubsan_mul_overflow,
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test_ubsan_negate_overflow,
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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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68
lib/ubsan.c
68
lib/ubsan.c
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@ -163,74 +163,6 @@ static void ubsan_epilogue(void)
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}
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}
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static void handle_overflow(struct overflow_data *data, void *lhs,
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void *rhs, char op)
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{
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struct type_descriptor *type = data->type;
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char lhs_val_str[VALUE_LENGTH];
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char rhs_val_str[VALUE_LENGTH];
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if (suppress_report(&data->location))
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return;
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ubsan_prologue(&data->location, type_is_signed(type) ?
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"signed-integer-overflow" :
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"unsigned-integer-overflow");
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val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
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val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
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pr_err("%s %c %s cannot be represented in type %s\n",
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lhs_val_str,
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op,
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rhs_val_str,
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type->type_name);
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ubsan_epilogue();
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}
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void __ubsan_handle_add_overflow(void *data,
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void *lhs, void *rhs)
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{
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handle_overflow(data, lhs, rhs, '+');
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}
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EXPORT_SYMBOL(__ubsan_handle_add_overflow);
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void __ubsan_handle_sub_overflow(void *data,
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void *lhs, void *rhs)
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{
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handle_overflow(data, lhs, rhs, '-');
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}
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EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
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void __ubsan_handle_mul_overflow(void *data,
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void *lhs, void *rhs)
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{
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handle_overflow(data, lhs, rhs, '*');
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}
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EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
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void __ubsan_handle_negate_overflow(void *_data, void *old_val)
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{
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struct overflow_data *data = _data;
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char old_val_str[VALUE_LENGTH];
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if (suppress_report(&data->location))
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return;
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ubsan_prologue(&data->location, "negation-overflow");
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val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
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pr_err("negation of %s cannot be represented in type %s:\n",
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old_val_str, data->type->type_name);
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ubsan_epilogue();
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}
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EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
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void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
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{
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struct overflow_data *data = _data;
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@ -8,8 +8,6 @@ ubsan-cflags-$(CONFIG_UBSAN_LOCAL_BOUNDS) += -fsanitize=local-bounds
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ubsan-cflags-$(CONFIG_UBSAN_SHIFT) += -fsanitize=shift
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ubsan-cflags-$(CONFIG_UBSAN_DIV_ZERO) += -fsanitize=integer-divide-by-zero
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ubsan-cflags-$(CONFIG_UBSAN_UNREACHABLE) += -fsanitize=unreachable
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ubsan-cflags-$(CONFIG_UBSAN_SIGNED_OVERFLOW) += -fsanitize=signed-integer-overflow
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ubsan-cflags-$(CONFIG_UBSAN_UNSIGNED_OVERFLOW) += -fsanitize=unsigned-integer-overflow
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ubsan-cflags-$(CONFIG_UBSAN_OBJECT_SIZE) += -fsanitize=object-size
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ubsan-cflags-$(CONFIG_UBSAN_BOOL) += -fsanitize=bool
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ubsan-cflags-$(CONFIG_UBSAN_ENUM) += -fsanitize=enum
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