-Wstringop-overflow is buggy in GCC-11. Therefore, we should disable
this option specifically for that compiler version. To achieve this,
we introduce a new configuration option: GCC11_NO_STRINGOP_OVERFLOW.
The compiler option related to string operation overflow is now managed
under configuration CC_STRINGOP_OVERFLOW. This option is enabled by
default for all other versions of GCC that support it.
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Makefile | 4 +++-
init/Kconfig | 12 ++++++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 2cfd71ae3a86..8adc611fb611 100644
--- a/Makefile
+++ b/Makefile
@@ -982,7 +982,9 @@ NOSTDINC_FLAGS += -nostdinc
# perform bounds checking.
KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
-KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow)
+#Currently, disable -Wstringop-overflow for GCC 11, globally.
+KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-option, -Wno-stringop-overflow)
+KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow)
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += -fno-strict-overflow
diff --git a/init/Kconfig b/init/Kconfig
index 9ffb103fc927..aaaa99a5d2a9 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -876,6 +876,18 @@ config CC_NO_ARRAY_BOUNDS
bool
default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC11_NO_ARRAY_BOUNDS
+# Currently, disable -Wstringop-overflow for GCC 11, globally.
+config GCC11_NO_STRINGOP_OVERFLOW
+ def_bool y
+
+config CC_NO_STRINGOP_OVERFLOW
+ bool
+ default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC_VERSION < 120000 && GCC11_NO_STRINGOP_OVERFLOW
+
+config CC_STRINGOP_OVERFLOW
+ bool
+ default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
+
#
# For architectures that know their GCC __int128 support is sound
#
--
2.34.1
On Thu, Nov 30, 2023 at 02:52:10PM -0600, Gustavo A. R. Silva wrote:
> -Wstringop-overflow is buggy in GCC-11. Therefore, we should disable
Can you add some links for this? For example, maybe this?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97490
Or discussions from -next builds?
> this option specifically for that compiler version. To achieve this,
> we introduce a new configuration option: GCC11_NO_STRINGOP_OVERFLOW.
>
> The compiler option related to string operation overflow is now managed
> under configuration CC_STRINGOP_OVERFLOW. This option is enabled by
> default for all other versions of GCC that support it.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
But yeah, let's get this landed to keep new warnings from appearing...
Reviewed-by: Kees Cook <[email protected]>
> ---
> Makefile | 4 +++-
> init/Kconfig | 12 ++++++++++++
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 2cfd71ae3a86..8adc611fb611 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -982,7 +982,9 @@ NOSTDINC_FLAGS += -nostdinc
> # perform bounds checking.
> KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
>
> -KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow)
> +#Currently, disable -Wstringop-overflow for GCC 11, globally.
> +KBUILD_CFLAGS-$(CONFIG_CC_NO_STRINGOP_OVERFLOW) += $(call cc-option, -Wno-stringop-overflow)
> +KBUILD_CFLAGS-$(CONFIG_CC_STRINGOP_OVERFLOW) += $(call cc-option, -Wstringop-overflow)
>
> # disable invalid "can't wrap" optimizations for signed / pointers
> KBUILD_CFLAGS += -fno-strict-overflow
> diff --git a/init/Kconfig b/init/Kconfig
> index 9ffb103fc927..aaaa99a5d2a9 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -876,6 +876,18 @@ config CC_NO_ARRAY_BOUNDS
> bool
> default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC11_NO_ARRAY_BOUNDS
>
> +# Currently, disable -Wstringop-overflow for GCC 11, globally.
> +config GCC11_NO_STRINGOP_OVERFLOW
> + def_bool y
> +
> +config CC_NO_STRINGOP_OVERFLOW
> + bool
> + default y if CC_IS_GCC && GCC_VERSION >= 110000 && GCC_VERSION < 120000 && GCC11_NO_STRINGOP_OVERFLOW
> +
> +config CC_STRINGOP_OVERFLOW
> + bool
> + default y if CC_IS_GCC && !CC_NO_STRINGOP_OVERFLOW
> +
> #
> # For architectures that know their GCC __int128 support is sound
> #
> --
> 2.34.1
>
--
Kees Cook
On 11/30/23 15:07, Kees Cook wrote:
> On Thu, Nov 30, 2023 at 02:52:10PM -0600, Gustavo A. R. Silva wrote:
>> -Wstringop-overflow is buggy in GCC-11. Therefore, we should disable
>
> Can you add some links for this? For example, maybe this?
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97490
>
> Or discussions from -next builds?
Done. :)
>
>> this option specifically for that compiler version. To achieve this,
>> we introduce a new configuration option: GCC11_NO_STRINGOP_OVERFLOW.
>>
>> The compiler option related to string operation overflow is now managed
>> under configuration CC_STRINGOP_OVERFLOW. This option is enabled by
>> default for all other versions of GCC that support it.
>>
>> Signed-off-by: Gustavo A. R. Silva <[email protected]>
>
> But yeah, let's get this landed to keep new warnings from appearing...
>
I just applied this to my -next tree.
> Reviewed-by: Kees Cook <[email protected]>
Thanks!
--
Gustavo