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ubsan: remove overflow checks

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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:
Andrey Ryabinin
2021-02-25 17:22:42 -08:00
committed by Linus Torvalds
parent d54ce6158e
commit 6aaa31aeb9
4 changed files with 0 additions and 136 deletions
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49
lib/test_ubsan.c
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@@ -11,51 +11,6 @@ typedef void(*test_ubsan_fp)(void);
#config, IS_ENABLED(config) ? "y" : "n"); \
} while (0)
static void test_ubsan_add_overflow(void)
{
volatile int val = INT_MAX;
volatile unsigned int uval = UINT_MAX;
UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
val += 2;
UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
uval += 2;
}
static void test_ubsan_sub_overflow(void)
{
volatile int val = INT_MIN;
volatile unsigned int uval = 0;
volatile int val2 = 2;
UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
val -= val2;
UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
uval -= val2;
}
static void test_ubsan_mul_overflow(void)
{
volatile int val = INT_MAX / 2;
volatile unsigned int uval = UINT_MAX / 2;
UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
val *= 3;
UBSAN_TEST(CONFIG_UBSAN_UNSIGNED_OVERFLOW);
uval *= 3;
}
static void test_ubsan_negate_overflow(void)
{
volatile int val = INT_MIN;
UBSAN_TEST(CONFIG_UBSAN_SIGNED_OVERFLOW);
val = -val;
}
static void test_ubsan_divrem_overflow(void)
{
volatile int val = 16;
@@ -155,10 +110,6 @@ static void test_ubsan_object_size_mismatch(void)
}
static const test_ubsan_fp test_ubsan_array[] = {
test_ubsan_add_overflow,
test_ubsan_sub_overflow,
test_ubsan_mul_overflow,
test_ubsan_negate_overflow,
test_ubsan_shift_out_of_bounds,
test_ubsan_out_of_bounds,
test_ubsan_load_invalid_value,